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AGRICULTURAL AND BIOLOGICAL PUBLICATIONS 
CHARLES V. PIPER, Consulting Editor 



APPLIED ENTOMOLOGY 






H/kQraW'Jj ill Book (hJm 

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APPLIED ENTOMOLOGY 

^A^ INTRODUCTORY TEXT-BOOK 

OF 

INSECTS IN THEIR RELATIONS TO MAN 



BY 

H. T. FERNALD, Ph.D. 

PROFESSOR OK ENTOMOLOGY, MASSACHUSETTS AGRICULTURAL COLLEGE, AND 

ENTOMOLOGIST OP THE MASSACHUSETTS AGRICULTURAL 

EXPERIMENT STATION 



First Edition 



McGRAW-HILL BOOK COMPANY, Inc. 

NEW YORK: 370 SEVENTH AVENUE 

LONDON: 6 & 8 BOUVERIE ST., E. C. 4 

1921 






Copyright, 1921, by the 
McGraw-Hill Book Company, Inc. 



m 25 W2> 



THE MAPI<E PRESS TORK PA 

g)C!.A624096 



to the memory of 
Professor Charles H. Fernald: 

the first teacher of Economic Entomology 
to college students, in this country.' 



PREFACE 

If one can judge from the answers to about fifty letters of inquiry 
sent to teachers of Entomology in colleges in the United States, the 
teaching of Entomology in this country at the present time is in a rather 
chaotic condition. Very few of the answers received show much in 
harmony in subject matter, methods of presentation, or even the line of 
training the students should receive by a course in the subject. 

The author believes that in agricultural colleges at least, two distinct 
groups of students need a knowledge in Entomology, and rather early in 
their course. One of these groups is composed of students who will 
never specialize in the subject but need it as part of an agricultural 
education, and particularly as a tool which they can use wherever insects 
are related to their special lines of work. They are not particularly 
interested in such details as the number of antennal segments in insects, 
the number of branches of the radial vein, or how important a pest on 
pigweed the insect is: they do not expect to identify insects beyond the 
order or family at most, relying on specialists available at the State 
Experiment Stations for such information. But they do desire a general 
knowledge of the broad outlines of the subject, and a rather complete 
knowledge of, and if possible, the ability to recognize particularly import- 
ant insect pests they are liable to meet in the course of their work. 

The other group consists of those who expect to specialize in the 
subject, becoming professional entomologists. Their needs will, of 
course, be different from those of the other group, but an introductory 
survey such as will meet the requirements of the rest will give the members 
of this group an excellent foundation for further and more detailed work. 

The present book is therefore offered as a classroom text for an 
introductory course in the subject, which shall give a general idea of 
insects, their structure, life histories and habits, with methods for the 
control of insect pests in general, followed by a more thorough study of 
the more important ones found in this country. For use, the writer 
believes that in few places will all of the text be assigned. Instead, the 
pests of the country as a whole (treated in large type) and those of the 
particular region concerned (selected from among those printed in smaller 
type) would naturally be the parts used in any one place, though the 
book as a whole should be fairly well applicable to all sections of the 
country. 

The author is of the opinion that to avoid too much monotony, it 
ma}^ prove wise to assign Chapters VI to IX inclusive, among those 



viii PREFACE 

immediately following. The treatment of the subject matter is such as 
to permit this. 

Many of the illustrations included are familiar. Where satisfactory 
illustrations are already available, it is questionable whether new ones 
are any gain, particularly when all are new to the student. In this 
connection the author desires to express his grateful appreciation of the 
kindness of Dr. W. E. Britton and the Connecticut Experiment Station, 
and of Prof. J. S. Houser and the Ohio Experiment Station, for the pro- 
vision of cuts from the publications of those Stations. He is much 
indebted to Prof. E. D. Sanderson for the use of cuts taken from ''Insect 
Pests of Farm, Garden and Orchard" and from Sanderson and Jackson's 
"Elementary Entomology," and to the publishers of these books, John 
Wiley and Sons, Inc., and Ginn and Company respectively, as well as to 
Dr. E. P. Felt who has kindly allowed the use of reproductions of illus- 
trations taken from his publications. Dr. J. W. Folsom's kindness and 
that of his publishers, P. Blakiston's Sons and Company in permitting 
the use of illustrations from Dr. Folsom's . book "Entomology with 
Reference to its Biological and Economic Aspects," is also much appre- 
ciated. Ginn and Company have kindly consented to the use of several 
illustrations from Linville and Kelly's "Textbook in General Zoology," 
and the side view of the parts of a grasshopper has been obtained by 
permission of those in charge of the Natural History Survey of Connecti- 
cut. The largest number of illustrations secured, however, has been 
obtained through the kind permission of Dr. L. 0. Howard of the U. S. 
Bureau of Entomology to use many which are the property of the Bureau. 
Photographs from various Experiment Station Reports and Bulletins 
have also been freely drawn upon. The source from which each illus- 
tration has been obtained is indicated in every case. To all the persons 
and companies above named, I desire to express my thanks. 

Any book such as this is necessarily a compilation. Probably there 
are very few if any entomologists in this country who have worked per- 
sonally on all the insects treated here. The only originality for it 
which can be claimed therefore, is in the selection of the various topics 
and their method of presentation. Errors have undoubtedly crept in, 
and the author will appreciate having his attention called to any which 
may be found. 

The author desires to express his appreciation of the aid in the pre- 
paration of this book given him by his associates. Dr. G. C. Crampton, 
Dr. W. S. Regan, and Mr. A. I. Bourne, who have gone over various 
parts of it and have criticized and advised on those which they have 
examined. Much of any value it may have is due to them, but for any 
errors and incorrect statements which may be found, the author assumes 
full responsibility. 

Amherst, March 1, 1921. H. T. FernaLD. 



CONTENTS 

Page 
Preface vii 

CHAPTER I 

Insects and other Animals 1 

The larger groups of animals — Their distinctive characters — The Arthropoda 
— ^Its characters — Animals included — Subdivisions of the group — Their 
distinctive characters — Tabular statement of the distinctive characters. 

CHAPTER II 

The Insect: Its External Structure 6 

The characters of insects — Number of segments in the embryo — In the 
adult — The hypodermis — Sutures — Plates — Form of head — Structures on 
the body — The antennae — Eyes — Mouthparts — Chewing mouthparts — - 
The thorax — Its appendages — Legs — ^Wings — The abdomen — Abdominal 
feet — Ovipositor — Other appendages. 

CHAPTER III 

The Insect: Its Internal Structure 15 

Digestive organs — Breathing organs — Circulatory organs — -The blood — 
Excretory organs — Nervous system — Sense organs — Reproductive organs. 

CHAPTER IV 

The Development of Insects 25 

Egg-laying and viviparous insects — Description of insect eggs— Hatching — 
Development of the insect — The Ametabolous development — Hemime- 
tabolous development — Holometabolous development — -Pupation and 
cocoon making — ^Transformation of the pupa — Emergence — Common 
names of Holometabolous larvae. 

CHAPTER V 

Losses Caused by Insects: Nature's Control Methods 32 

Amount of the loss not generally realized — Its average amount — To crops — 
To animals and their products — To forests and their products — To stored 
materials — ^By disease — Total loss — Losses increasing — Causes — Intro- 
duction of foreign insect pests — Reduction in abundance of insectivorous 
birds — A theoretic state of equilibrium upset by civilization — Nature's 
methods too slow — Artificial methods necessary. 

CHAPTER VI 

Artificial Methods of Control 38 

Two groups of methods — Farm practice — Healthy crops — Crop rotation- 
Plowing — Time of planting — Resistant varieties of plants — Trap crops — 
Special methods — Hand picking — Repellents — Trap lanterns — Burning — 
Heat — Miscellaneous methods. 



X CONTENTS 

CHAPTER VII 

Page 

Insecticides in General: Stomach Poisons 43 

Materials classified — Conveyance — Dusts — Sprays — Arsenic — ^Disadvan- 
tages — ^ Paris green — Disadvantages — Standard formula — Variations — 
Arsenate of lead — Standard formula — Arsenate of lime — Standard formula — 
Poison baits — Hellebore — Commercial Sodium Fluorid. 

CHAPTER VIII 

Contact Insecticides 49 

Purposes of contact insecticides^ — Kerosene emulsion — Miscible oils — 
Whale-oil soap — Common soap — Nicotine — Nicotine sulfate — Lime sulfur 
wash — Dry sulfur compounds — Sulfur — Pyrethrum, insect powder, or 
buhach. 

CHAPTER IX 

Insecticides and Fungicides: Fumigation 54 

Combinations of spray materials — Of insecticides — Of insecticides and 
fungicides — Injurious combinations — Fumigation — Nature of its action — 
Limits of availability — Carbon disulfid — Nicotine — Sulfur — Hydrocyanic- 
acid gas. 

CHAPTER X 

The Relationships of Insects 59 

Classification — The development of animals in the past — Artificial and 
natural classifications — ^The original insects — The development of diversity 
— Resultant groups — Relations of species, genera, families etc. — A sample 
tree-like classification — Table of classification. 

CHAPTER XI 

The Apterygota 62 

General structure — -Distinctive characters — ^General description — Divisions 
of the group — Order Thysanura — Distinctive characters — The Silver Fish — 
Order CoUembola — General features — Distinctive characters — General 
account. 

CHAPTER XII 

The Pterygota. The Ephemerida 65 

General considerations on the Pterygota — The Ephemerida — General 
description and structure — Distinctive characters — Life and habits — 
Importance. 

CHAPTER XIII 

The Odonata 68 

General description and structure — Distinctive characters — Groups of 
dragon-flies — Habits — Their life and food — Importance — Abundance. 

CHAPTER XIV 

The Plecoptera 72 

General description of the group — Distinctive characters — Life and habits — 
Abundance — Economic importance. 



CONTENTS xi 

CHAPTER XV 

Page 

The Embiidina 74 

General description — Economic importance. 

CHAPTER XVI 

The Orthoptera 75 

General description — Structure — Division into two sections — The Cursoria 
— Distinctive characters — Families considered — ^The Blattidae — Descrip- 
tion of Roaches — The German Roach — The American Roach — The Aus- 
tralian Roach — The Oriental Roach or "black beetle" — ^Control of Roaches 
— The Mantidae — General considerations — Common Mantids — The Phas- 
midse — General description of appearance, life history and habits — Eco- 
nomic importance — Control — The Saltatoria — General features — The Acri- 
didae — Description of grasshoppers — Abundance — Economic importance — 
Control — Kinds of grasshoppers — Sounds produced — Organs of hearing — 
The Tettigoniidse — -General description of the family, habits, life history, 
etc. — Economic importance — ^The Gryllida; — General statements — Sounds — 
Ears — Economic importance — Kinds of crickets — Tree crickets — Control. 

CHAPTER XVII 

The Isoptera 91 

The colony — Its composition — ^Castes — Structures — Distinctive characters 
— Food — Swarming — Common species — Life and habits — Injuries — Control 
— ^Zoraptera. 

CHAPTER XVITI 

The Dermaptera 95 

General description — Distinctive characters — Importance — Habits — 
Different species — The European earwig — Injuries — Control. 

CHAPTER XIX 

The Coleoptera 98 

Structure — Distinctive characters — Life histories and habits — ^Division into 
Coleoptera vera and Rhynchophora — Coleoptera vera — Lampyridae — 
Carabidte — • Cicindellidse — Dytiscidse — Gyrinidae — -Hydrophilidae — ^Staphy- 
linidae — 'Silphidte — Dermestidae — Larder beetle — Buffalo Carpet beetle — 
— Black Carpet beetle — Control — Buprestidae — Flat-headed Apple-tree 
Borer — ^Elateridae — -Wireworms — control — Scarabaeidse — June bugs — Rose 
chafer — -Japanese Beetle — Chrysomelidse — Colorado Potato Beetle — 
Change of food a possible pest producer — Striped Cucumber Beetle — Corn- 
root Worms — ^Flea Beetles — Asparagus Beetles — Grape Root Worm — Elm 
Leaf Beetle — Tortoise Beetles — Bruchidae — Pea Weevil — Bean Weevil — 
Broad Bean Weevil — Control of Weevils — Cerambycidae — Round-headed 
Apple-tree Borer — Coccinellidae — Tenebrionidae — Yellow Meal-worm — 
Meloidae — Rhynchophora — Plum Curculio — Plum Gouger — Cotton Boll 
Weevil— White Pine Weevil— Alfalfa Weevil— Potato-stalk Weevil— Sweet- 
potato Weevil — Ipidae — Fruit-tree Bark Beetle. 



xii CONTENTS 

CHAPTER XX 

Page 

The Strepsiptera 150 

General description — Distinctive characters — Habits — Life history — Abun- 
dance — Importance. 

CHAPTER XXI 

The Thysanoptera 153 

General features — Structure — Distinctive characters — Habits — Subdivisions 
— Wheat Thrips — Onion Thrips — Pear Thrips — Citrus Thrips. 

CHAPTER XXII 

The Corrodentia 159 

General description — Structure — Distinctive characters — Book lice — 
Psocids — Importance of the group. 

CHAPTER XXIII 

The Mallophaga 161 

General features — Distinctive characters — Habits — Poultry lice — Control. 

CHAPTER XXIV 

The Anoplura 164 

Description — Distinctive characters — Distribution — Life history — Body 
louse — -Relation of lice to disease — Crab louse — Lice on domestic animals- 
Control. 

CHAPTER XXV 

The Hemiptera 168 

General characters — Structure of mouthparts — Distinctive characters — 
Distribution — Habits — Pentatomidse — Harlequin Bug — Cydnidse — ^Coreidae 
— Squash Bug — Pyrrhocoridse — Cotton Stainer — ^Lygseidse — Chinch Bug 
— The diseases of Insects — Tingitidae — Miridse — Meadow Plant Bug — Tarn- 
ished Plant Bug — ^Phymatidse^-Reduviidie — Cimicidse — Bedbug — Gerridfe 
— Notonectidse — ^Corixidae — Nepidaj — Belostomida;. 

CHAPTER XXVI 

The Homoptera 186 

General statements — Distinctive characters — ^Variations in habits etc. — 
Honey dew — Classification of the order — Cicadida? — Periodical Cicada or 
17-year Locust — -Leaf Hoppers and Tree Hoppers — -Apple Leaf hoppers — 
Rose Leaf hopper — ^Chermidse — Pear Psylla — Aphididae in general — Apple 
Aphids— Grape Phylloxera — Corn Root Aphis — Aleyrodida; — Coccidse 
in general — Armored Scales — Oyster-shell Scale — ^Scurfy Scale — San Jos6 
Scale — Rose Scale — Pine Leaf Scale — Purple Scale — Red Scale — Soft 
Scales — Black Scale — Terrapin Scale — Cottony Maple Scale — Hemispherical 
Scale — Mealy Bugs — Citrus Mealy Bug — Long-tailed Mealy Bug — Cottony 
Cushion Scale — Introduction of enemies of introduced pests. 



CONTENTS xiii 

CHAPTER XXVII 

Page 

The Neuroptera 221 

General features — Distinctive characters — Economic value — -Sialida? — 
Corydalis — Chrysopidse or Aphis lions — Raphidiidse — Mantispidae — Myrme- 
leonidse or Ant lions. 

CHAPTER XXVIII 

The Trichopteha 22(3 

General description — Distinctive characters — Life and habits — Larval cases 
— Importance. 

CHAPTER XXIX 

The Lepidoptera 230 

General features — Structure — Mouthparts — ^Distinctive characters — -Diver- 
sity in the order — Life history and development in general — Cossida) — 
Leopard Moth — Tineida? — Clothes moths and their control — Codling Moth 
— -.^geridiE — Peach Borers — Squash-vine Borer — Gelechiida; — Angoumois 
Grain Moth — Pterophoridaj — Pyralida; — Bee Moth — European Corn Borer 
— Limacodidse — Psychida? — Geometridae -r- Canker worms — Bombycida; — 
Lasiocampidae — Apple-tree Tent-caterpillar — Forest Tent-caterpillar — Ly- 
mantriidae — White-marked Tussock Moth — Antique or Rusty Tussock 
Moth— Gypsy Moth — Brown-tail Moth— Notodontida;^Dioptida? — Cali- 
fornia Oak Worm — ^Noctuidse in general — -Cotton Worm — Corn-ear Worm 
— Army Worm — Fall Army Worm — Cutworms — Arctiidse — Fall Web-worm 
— Ceratocampida; — Saturniida? — Sphingidic — Tobacco and Tomato Worms 
— The Butterflies — Hesperiida; — Lyca^nidse — Danaida? — -Ny mphalida; — - 
Satyridse — Pieridae — Imported Cabbage Butterfly — ^Sulfur butterflies — The 
spreading over the country of introduced insects — Papilionida? — Black 
Swallow-tail butterfly. 

CHAPTER XXX 

The Mecoptera 300 

General features — Distinctive characters — Habits — Food — Importance. 

CHAPTER XXXI 

The Diptera 301 

General description — Structure — Mouthparts of adult — Larvae — Pupse — 
Distinctive characters — Size and importance of the group — Tipulidae — 
Culicidse — House Mosquito — Malarial Mosquitoes — Relation to malaria — - 
Yellow Fever Mosquito — Control of mosquitoes — ^Itonididaj — Clover- 
flower Midge— Hessian Fly — Wheat Midge — Tabanidaj — Simulidae — 
Asilidse — Syrphidse — ffistrida; — ^Ox Warbles — -Trypetida; — Apple Maggot — 
Muscidaj — House Fly — Its relation to disease — Screw Worm Fly — Sarco- 
phagida? — Tachinida? — Tsetse Flies — Anthomyiidae — Cabbage Maggot — 
Onion Maggot — ^Pupipara — ^Sheep Tick. 

CHAPTER XXXII 

The .Siphonaptera 333 

General description — Structure — Distinctive characters — Food — Life his- 
tory and habits — Relation to disease — Control — "Sticktight flea" — Chigoe. 



xiv CONTENTS 

CHAPTER XXXIII 

Page 

The Hymenoptbra 338 

General description and structure — Terebrantia and Aculeata — Develop- 
jnent — Distinctive characters — Importance — Tenthredinoidea — Currant 
WTorm — ^Pear Slug — Wheat Stem Borers — ^Horn-tails — Ichneumonoidea — 
Their importance — Methods of work — Long-tailed Thalessa — Cynipoidea — 
Gall production — Alternation of generations — Inquilines — Parasites — Impor- 
tance of galls — Chalcidoidea — Habits— Wheat Straw Worm — Wheat Joint 
worm — Clover-seed Chalcis — Fig Blastophaga — Pteromalus puparum — 
Serphoidea — Long-tailed Pelecinus — Variation in habits of parasitic Hymen- 
optera— Chrysidoidea — Sphecoidea — Vespoidea — Progressive development 
as illustrated by Wasps — Apoidea — Solitary bees — Leaf-cutter bees — 
Carpenter bees — Bumble bees — Honey bee — Life of a Honey bee colony — 
Swarming — Value of bee products — Formicoidea — Composition of ant 
colonies — Location of colonies — Swarming — Establishment of new colonies — 
Ants and plant lice, etc. — Unusual habits — Argentine Ant — House Ants — 
Ants in lawns. 



APPLIED ENTOMOLOGY 

CHAPTER I 
INSECTS AND OTHER ANIMALS 

Among the larger groups of animals now recognized by science, the 
one known as the Chorda ta is naturally the most familiar, including the 
mammals, birds, reptiles, fishes, besides numerous forms less well known. 
Another group, also familiar, and called the Mollusca, includes the snails, 
clam etc., while a third, the Annulata, contains most of the more 
commonly seen worms. The starfish and sea urchins, often seen at the 
seashore, belong with other similar animals, to a fourth group called the 
Echinodermata, and a multitude of tiny beings almost all too small to be 
seen without the aid of a microscope, are included in the group Protozoa. 
A sixth large group is composed mainly of soft, jelly-like animals, the 
more common larger members being called jelly-fish, and to this the 
name Coelenterata is applied, and several other groups of less familiar 
forms are also known. 

The largest group of all, however, is the Arthropoda, its members 
found in the seas, in fresh water, on land, or even flying freely; a group 
with remarkable differences of structure, and so abundant that all the 
other animals taken together are less than one-sixth as many as the 
Arthropods. Well-known members of this group are the lobsters, cray- 
fish and crabs; scorpions, spiders, mites, ticks and "daddy long legs;" 
the centipedes and millipedes; and last and most abundant of all, the 
Insects. 

No one feature will serve to separate the Arthropods from all other 
animals, but the possession by an animal of several of those here described 
will enable the observer to determine in each case whether he is examin- 
ing one of this group. In Arthropods the body is composed of a series of 
more or less similar pieces or segments, placed one behind another, the 
line of attachment of these to each other being usually somewhat evident 
on parts of the body at least. This character is also shown, and indeed 
more clearly, in some members of the Annulata, such as the common 
earthworm. Another character of the Arthropods is the presence of 
jointed legs (or appendages of some kind), as is indicated by the name 
of the group, and these are not possessed by Annulates. The surface of 
the body is covered by a secretion which hardens on exposure to the air, 

1 



APPLIED ENTOMOLOGY 



forming an outside shell or external skeleton (exo-skeleton), there being 
practical^ no internal supporting structures except as ingrowths from 
the outside. In the possession of this external skeleton these animals 

have a seeming resemblance to the 
shells (Mollusca), but the materials 
of which it is composed are quite 
different, being largely calcium car- 
bonate in the Mollusca, and chitin 
which somewhat resembles horn in 
its nature, sometimes with calcareous 
salts deposited in it, in the Arthro- 
poda. In its simplest members the 
Arthropod body is also practically 
bilaterally symmetrical, though this 
condition is concealed somewhat by 
secondary changes in many of the 
group. The possession of a bilaterally 
symmetrical body consisting of a 
series of segments; an exoskeleton of 
chitin, and the presence of jointed 
legs, are then, distinctive features of 
the Arthropods. 

To separate the various groups of Arthropods, other characters must 
be used. Aside from several small sections not often seen, there are five 
large and important divisions which call for recognition. These are the 
Crustacea, including the lobster, crab, beach flea, sow bug and many 




Fig. 1. — Crayfish {Crustacea); about 
one-half natural size. {Original.) 





Fig. 2. — "Sow-bug; a crustacean 
living on land; about natural size. 
{Original'^ 



Fig. 3. 



-Millipede {Diplopoda); natural size. 
{From Folsom.) 



others; the Diplopoda or Millipedes; the Chilopoda or Centipedes; the 
Hexapoda or Insects; and the Arachnida, including the scorpions, pseudo- 
scorpions, spiders, mites, ticks, etc. 



INSECTS AND OTHER ANIMALS 3 

The Crustacea (Fig. 1) are mainly water-inhabiting animals which 
breathe either by gills, or, in the smaller forms, through the surface of 
the body. In those cases where its members hve on land (Fig. 2) the gills 
are still present, though in a somewhat modified condition. They have 
numerous pairs of legs and generally two pairs of antennae (jointed 
"feelers"). Often some of the body segments are fused with the head 
to form a cephalothorax. 

The Diplopoda (Fig. 3) are land animals breathing by air tubes open- 
ing on the sides of the body and permitting the air to pass in to all the 
internal parts of the animal. The head bears a pair of antennae and is 
followed by a series of segments all practically alike and each, except 




Fig. 4. — Centipede (Chilopoda) ; about three-quarters natural size. {Original.) 



the first three, with two pairs of legs. The reproductive organs open 
far forward on the body. In most of the more common members of 
this group the body is quite cylindrical and when disturbed the animal 
usually curls up in a sort of close spiral. Small" Diplopods about the 
diameter of the lead of a pencil and gray in color are often found boring 
into potatoes and roots in the ground in the fall,, and are sometimes 
wrongly called wireworms. The common name "millipede" refers to 
the large number of legs possessed by these animals. 

The Chilopoda are also land animals (Fig. 4). Like the Diplopods 
they have antennae; breathe by air tubes, and the body segments are 
practically all alike. The general form, however, is rather flattened; 
each segment bears only one pair of legs, and the reproductive organs 
open at the hinder end of the body. The front leg on each side is modi- 



4 



APPLIED ENTOMOLOGY 



fied to serve as a poison claw. The numerous legs present in these 
animals has resulted in their receiving the common name '' centipede." 





Fig. 5. — Hairy Spider (Arachnida); about Fig. 6. — Large bodied Spider (AracAnida), 
natural size. (Original.) about natural size. (Original.) 





Fig. 7. — Adult female castor-bean Tick Fig. 8. — Adult female European dog 

(Arachnida); natural size. (From U. S. Tick (Arachnida) ; na.tuTa\ size. (FromU. S. 
D. A. Farm. Bull. 1057.) D. A. Farm. Bull. 1057.) 




Fig. 9. — Grasshopper (Insecta); with wings spread. (From Folsom.) 

The Arachnida (Figs. 5, 6, 7 and 8) generally have the segments of the 
body grouped into two sections called the cephalothorax and abdomen. 



INSECTS AND OTHER ANIMALS 5 

No antennae are present and the eight legs are all attached to the first- 
named section. They breathe either by air tubes somewhat similar to 
those of the other groups; by sacs containing many thin plates resembling 
leaves of a book, whence these structures take the name of book-lungs; 
or, in the smallest forms, directly through the body surface. In the 
mites there is no evident division of the body into sections. Though 
most of the group are land forms, a few are aquatic. 

In the Hexapoda or Insects (Fig. 9) the segments of the body are 
grouped in three distinct sections; the head, thorax and abdomen. A 
pair of antennae is (with rare exceptions) present on the head; the six 
legs are attached to the thorax as are the four wings usually present; 
the animals breathe by air tubes; and while living under a great diversity 
of conditions, the group as a whole is emphatically a terrestrial one, 
though in many cases their early life is spent in water. 



Distinctive Characters of the 


Main Arthropod Groups 




W here 
found 


Body divisions 


\ntennse 


Legs 


Breathe by 


Reproduc- 
tive organs 
open 


Crustacea .... 


Mainly in 
water 


Head and body: 
often a cepna- 
lothorax 


Two pairs 
generally 


Numerous: may 
be built for 
swimming 


Gills or through 
body surface 
(rarely by air 
tubes; 


Well forward 


Diplopoda. . . 


On land 


Head and body 


One pair 


Many: two 
pairs on most 
body seg- 
ments 


Air tubes 


Near head 


Chilopoda. . . . 


On land 


Head and body 


One pair 


Numerous: one 
pair on each 
body segment 


Air tubes 


Next to last 
body seg- 
menl 


Arachnida. . . 


Mainly on 
land 


Cephalothorax 
and abdomen 
(no divisions 
in a few cases) 


None 


Eight: joined 
to cephalo- 
thorax 


Air tubes, book- 
lungs or body 
surface 


Front part of 
abdomen 
(a few ex- 
ceptions) 


Hexapoda. . . 


Mainly on 
land 


Head, thorax, 
abdomen 


One pair 


Six: joined to 
thorax 


Air tubes 


Near hind end 
of abdomen 



CHAPTER II 

THE INSECT : ITS EXTERNAL STRUCTURE 

Bringing together the facts about insects ah-eady stated, we find that 
an adult insect is a bilaterally symmetrical animal consisting of a series 
of segments one behind another, and that these segments are grouped 
into three regions, the head in front, followed in order by the thorax and 
the abdomen (Fig. 10). Covering the animal is a skeleton, shell-like in 
that it encloses the body, but horny in its nature. Attached to the seg- 



V^ad "m 



OTOX 



i compound eue 
oceUus ' -ipTOTvoVum j oudiTon^ or^an y^^^y/ 




orAtnnae 



"tfttSUS 



Fig. 10. — Side view of Grasshopper with parts named. {From Walden, Conn. Geol. & 

Nat. Hist. Sun., Bull. 16.) 

ments are three pairs of jointed legs, a pair of antennae, mouth parts and 
usually two pairs of wings. It breathes through air tubes, and the 
reproductive organs open near the hinder end of the body. 

The adult insect does not show all the segments of which its body is 
composed. In the embryo evidences of 21 have been found, ^ but as the 
animal progresses toward maturity some of these fuse with others. The 
head of the adult, though apparently consisting of only one segment, is 
now believed to be the product of the fusion of six: the three found in 
the adult thorax seem to have always been that number; and the abdo- 
men, composed of 12 segments in the embryo appears to have been re- 
duced in the adult to a number varying from three to 11, partly by a 

^ Some investigators believe that 22 segments are present, the head consisting of 
seven, but this view is not universally accepted. 

6 



THE INSECT: ITS EXTERNAL STRUCTURE 



O/Tf.v 




IW(.J>. 



labp. 



'Ibr 



Fio. 11. — Front view of huiid of a Grass- 
hopper showing a hypognathous head ; ani, 
antenna; c. <■., compound eye; ch, cheek; c/, 
clypeus;//-, frons; lah. -p., labial palpus; /br., 
labrum; md, mandible; mx. p., maxillary 
palpus; 0, ocelli; v, vertex. 



process of fusion, partly by a sort of telescoping or the gradual shifting 
of one segment within another until it is partly or entirely concealed. 

The skeleton covering the body is generally considered to be a secre- 
tion from the outside living layer of cells, the hypodermis. This secre- 
tion gradually hardens on exposure 
to the air, providing the support 
necessary for the soft parts within. 
Chemically it consists of chitin 
(C15H26N2O10), which remains thin 
and flexible at the movable joints 
and wing articulations, but else- 
where becomes thicker and usually 
darker in color. Here and there 
over its surface are impressed lines 
like scratches, very definite and 
fixed in position in most insects, 
and these are termed sutures, and 
are of great use as landmarks in 
description. These sutures have 
such an arrangement that in an 
ordinary segment of the body its 
upper surface has often been re- 
garded as a plate or sclerite, the notum; one at each side, the pleuron; 
and one beneath, the sternum. These plates may have sutures sub- 
dividing them. 

In the head the sutures are few in number, and only a few plates or 
sclerites are generally in evidence. In the thorax they are more numer- 
ous, while in the abdomen often 
only a dorsal and ventral sclerite 
for each segment are found. 
Occasionally the weakly chitin- 
ized areas are quite large (queen 
white ant) and elastic. Usually 
the elasticity of these places, as 
for example, the portions con- 
necting the segments, is rather 
slight. Spines, hairs, scales or 
other structures are often present 
on the chitin, sometimes entirely 
concealing its surface and its 
sutures. 
The heads of different insects vary much in form and in the location 
of the mouth (Fig. 11). In some cases this is on the underside (see Fig. 
10), while in others (Fig. 12) it is practically on the front. Heads with 




Fig. 12. — Side view of Beetle {Lucanus 
dama Fab.) showing a prognathous head. 
{Original.) 



8 



APPLIED ENTOMOLOGY 



the mouth beneath are called hypognathous : those with it in front are 
prognathous. 

Structures found on the head are a pair of antennae, the two compound 
eyes, ocelli, and the mouth parts. On the thorax are the wings and legs; 
and on the abdomen are various organs such as the ovipositor, sting, cerci, 
styH, etc., present in some cases; absent in others. 






Fig. 13a. — Different forms of insect antenna*. (Orifjinal.) 

Antennae are nearly always present. They are usually slender, jointed 
and therefore more or less flexible organs, varying greatly in the number of 
segments composing them. They are sometimes very short; sometimes 
long; often thread-like; sometimes enlarged near the tip; in many cases 
with fine branches either on one or both sides, so that they resemble 
feathers or plumes; rarely they fork; in fact are of 
many forms (Fig. 13). Sense organs are present on 
them for the sense of touch, and probably also for 
smell and hearing, at least in some cases. 

The eyes are of two kinds. There is a pair of com- 
pound eyes, each of which is a group of similar struc- 
tures which usually are hke tall, slender pyramids in 
form. Only the bases of these pyramids show on the 
surface,' the remainder being within the head. The 
bases, closely pressed together, are usually more or 
less hexagonal, and their outlines can often be easily 
seen with a magnifying glass. They are called facets, 
and the eyes themselves are sometimes termed the 
facetted eyes. 

The other kind of eyes, called ocelli, may be absent, 
or if present, may vary in number in different insects, 
three being perhaps the most usual. Each, as seen from the surface, 
is a nearly circular, convex spot about the size of one of the facets of a 
compound eye. It may be larger than this, but is never equal to an 
entire compound eye in size. In some cases a cluster of ocelli or of the 
pyramids of the compound eyes is found, not closely pressed together 




Fig. 136. — An- 
tennae of Cecropia 
Moth. iSamia ce- 
cropia L.) About 
twice natural size. 
(Original.) 



THE INSECT: ITS EXTERNAL STRUCTURE 



9 



but somewhat separated, and such groups are called agglomerate eyes. 
The chitin of the surface of the body is transparent where it covers 
the surface of an eye, permitting access of light to the sensory struc- 
tures within: elsewhere it is usually pigmented and rather opaque. 

The mouth parts of insects vary extremely in their structure. Appar- 
ently the original mouth parts were for biting and chewing, and this 
type is very common. In some groups, however, they have been trans- 
formed into a sucking apparatus. Biting mouth parts, being the more 






Fig. 14. — Three types of insect mandibles, greatly enlarged. Somewhat diagrammatic. 

(Original.) 

primitive and simple, are described here, while sucking mouth parts 
having been differently transformed in different groups will be taken up 
in connection with those groups. 

In front of (in hypognathous heads), or above the mouth opening 
(prognathous heads) is the front lip or labrum. It is a thin flap, hinged 
to the skeleton of the head and 
moves forward and backward. It 
is often more or less divided by a 
central notch at the middle of its 
free edge. Its inner surface, form- 
ing the roof of the mouth, is often 
called the epipharynx. 

At the sides of the mouth open- 
ing, immediately behind the lab- 
rum, is a pair of jaws, the mandibles. 
These differ greatly in form in 
different insects (Fig. 14). They 
are often stout, heavy structures 
with crushing faces bearing blunt 
projections or teeth; sometimes they 
are long, curved and rather slender. 
In general their form is adapted to the feeding habits of the insect. 

Immediately behind each mandible at the side of the mouth is a 
second appendage, the maxilla. This differs markedly from the mandible, 
being much weaker, and composed of a number of pieces (Fig. 15). The 
tips and outer internal margins of the maxillae usually bear numerous 




Fig. 15. — Two types of insect maxilla 
greatly enlarged. Somewhat diagrammatic. 
(Original.) 



10 APPLIED ENTOMOLOGY 

spines or hairs, but this condition varies according to the nature of the 
food of the insect. Attached on the outer side of each maxilla not far 
from where the latter articulates with the head, is a sort of tiny antenna- 
like structure consisting of from one to six (usually five) segments, which 
is called the maxillary palpus. The function of the maxillae appears to be 
to hold and retain the food in the mouth while it is being worked upon 
by the mandibles, and also to aid these in breaking it up. The presence 
of sense organs on the maxillary palpi suggests that these are possibly 
concerned with the sense of smell. Both mandibles and maxillae move 
sideways. 





Fig. 16. — Two types of insect labium much enlarged. Somewhat diagrammatic. 

(OriginaL) 

Behind the maxillae and closing the mouth opening behind, is the 
hinder lip or labium (Fig. 16). This was evidently once a pair of jaws 
somewhat similar to the maxillae, but with no mouth cavity between to 
separate them., their inner edges have grown together to varying 
degrees in different insects. In some, only one or two of the pieces 
nearest the head have fused: in others, fusion all the way to the tip 
has been accomplished, and all intermediate stages also occur, thus 
producing a structure which now moves forward and backward like the 
front lip, but which may be complete, partially, or almost entirely cleft 
in the middle line. 

Like the maxilla the labium has a palpus on each side arising from 
near its base, and composed of three (rarely four) segments. The func- 
tion of these labial palpi appears to be similar to that of the maxillary 
palpi. 

Near the base of the labium on its inner or mouth side there is fre- 
quently a fleshy swelling more or less covered by bristles or hairs, which 
is called the hypopharynx, lingua or tongue. It varies greatly in size 
and form. 

The thorax has its three segments usually quite clearly marked. 
Each segment bears a pair of legs, but the prothorax, or first of the 
three behind the head, bears no wings. On the second or mesothorax, 
and on the third or metathorax, both wings and legs occur in the majority 



THE INSECT: ITS EXTERNAL STRUCTURE 



11 



of insects. There is a tendency in some groups, carried farthest in the 
higher Hymenoptera, for the first segment of the abdomen to consohdate 
more closely with the metathorax than with the second abdominal seg- 




FiG. 17. — Different forms of insect legs. A. Cicindela sexgullala Fab. (beetle); B, 
Nemohius fasciatus De G. (cricket) hind leg; C, Stagomantis Carolina L. (Mantis) fore leg; 
D, Pelocoris femoratus P. B. (carnivorous bug) fore leg; E, Gryllolalpa borealis Burm. 
(mole cricket) fore leg; F, Canthon Icevis Dru. (a digging beetle) fore leg; G, Phanceiis 
carnifex L. (a digging beetle) fore tibia and tarsus of female; H, same, fore tibia of male; 
/, Dytiscus fascivenlris Say, male (water beetle) fore leg; C, coxa; /, femur; s, spine; t, 
trochanter; th, tibia; is, tarsus. {From Folsom.) 

ment, which in such cases is often slender and gives thereby a semi- 
detached appearance to the rest of the abdomen, as though the line of 
division between thorax and abdomen were at that place instead of 



12 



APPLIED ENTOMOLOGY 



tb 



farther forward. The first abdominal segment when seemingly more a 
part of the thorax than of the abdomen is called the median segment or 
propodeum. 

The three pairs of legs may be quite similar, or differ widely, according 

to the uses to which they are put. In running and walking insects they 

are usually most similar; but when for example, the fore legs are used 

for capturing other insects, their form will depart greatly from that of the 

others. The jumping power of the grasshopper is 

due to the great development of its hind legs as 

compared with its others. Different types of legs 

are shown in Fig. 17. 

Whatever may be the variations in form and 
details of the legs, all are composed of a definite 
number of pieces or segments, connected by hinge 
joints so arranged that by combining the motions of 
these, a leg can be placed in nearly any position 
desired. 

The leg (Fig. 18) is composed of a coxa, a tro- 
chanter (two in a few cases), a femur, a tibia and a 
tarsus. The last is really not a single segment but 
a row of from one to five, small, and on the whole 
rather resembling each other. 

The coxa is the segment which articulates with 
the body, frequently partly lying in a more or less 
cup-shaped hollow of the latter. It may be short or 
long, is generally freely movable on the body, and 
ix)werful. The trochanter is usually small and may 
not be visible on all sides of the leg. It is followed 
by the femur, generally the largest and stoutest, but 
not often the longest leg segment. The tibia is in 
most cases quite long, more slender than the femur, 
and often provided with downwardly projecting 
spines- or other structures which are of assistance to 
the insect in climbing plant stems and other objects, 
to help prevent slipping. The tarsal segments are 
generally rather small, short, tend to be broadest at their outer ends, and 
vary greatly in details of structure. At the end of the last a pair of 
claws is generally found, and between them a sort of pad or cushion, the 
pulvillus. Sometimes there are three of these, in which case the outer 
ones are called the pulvilh and the middle one the empodium. Where 
the tarsi are reduced to a small number of segments, only one claw may 
be present. 

The wings are chitinous outgrowths from the body which vary much 
in size and form in different insects. Each consists of two delicate 



M 

Fig. 18. — Leg of a 
Beetle showing parts. 
c. coxa, cl, claws; /, 
femur; .s, spine or 
spur; t^t^, tarsal seg- 
ments; tb, tibia; 
tr, trochanter, {from 
Folsom.) 



THE INSECT: ITS EXTERNAL STRUCTURE 



13 



membranes in contact with each other except along certain lines (Fig. 
19). Along these hnes each membrane thickens and also rises above the 
general surface, so that if the two membranes could be separated and 
examined from the inner surface, they would appear uniform except for 
grooves with thickened sides and bottoms, running here and there. 



Fig. 19. — Diagram of cross-section of an insect wing showing the two membranes 
somewhat separated and the ways in which the veins are formed. (Modified from Wood- 
worth.) 

When the membranes are brought together again, these grooves com- 
bining form hollow rods which, being stronger than the rest of the mem- 
brane, serve as its support and hold it stiff. These hollow rods are 
usually called veins or nerves, though they are nothing of the sort. 
The main and largest veins arise at the base of the wing and extend 
outward, diverging as they go, and some branch several times before they 

/A 




a.an. 

Fig. 20. — Diagram of the margins and veins in the wings of moths. A, apex; a. an, 
anal angle; c, costa; c.c, closed cell; /, frenulum; i.n, inner margin; o.m, outer margin; d, 
vein. {Original.) 

reach the wing margin (Fig. 20). Cross veins also occur, connecting the 
radiating main veins or their branches. Areas of membrane between 
veins are termed cells and where entirely surrounded by veins are called 
closed cells. These may be relatively few or many, according to the 
number of veins and their branches present. The arrangement and 
number of the chief veins and their branches are of importance in 
identifying insects. 



14 



APPLIED ENTOMOLOGY 



There is usually a point or tip called the apex, somewhere along the 
margin of the wing, though frequently the outline is so rounded that the 
exact apex is uncertain. The front margin of the wing from where it 
joins the body to where the edge begins to turn backward (in an extended 
wing) is called the costa. 

Wings are entirely absent in some groups of insects, and it is probable 
that these are the direct descendants of the earliest forms, before wings 
were developed. In other cases where they are absent this is associated 
with a parasitic life where wings might be a distinct disadvantage, or 
with pecuHar habits which would render them useless or even inconvenient, 
and in such cases they appear gradually to have become lost. In the 
flies the hinder pair is modified, forming small structures not wing-Uke, 
called halteres. 

The abdomen does not usually show great differences in its seg- 
ments except those near the hinder end, which may be modified for 
various purposes. Generally a dorsal plate and a ventral plate are the 
only two skeletal plates evident in a segment. Small openings, usually 
a pair in each, or at least in most, of the segments are the openings of the 
breathing organs, and these also occur on some of the thoracic segments 
where thev are ordinarilv less noticeable than on the abdomen. 




Fig. 21. — Larva of Cecropia Moth showing abdominal legs. Two- thirds natural size. 

{Original.) 

Legs are very rarely present on the abdomen in adult insects, but are 
often found in the earlier stages (Fig. 21), At the end of the abdomen 
in the females of those insects which lay their eggs within objects, is a 
combination of pieces known as an ovipositor. It usually consists of 
about three pairs of parts, long or short, slender or stout as the case may 
be, for the purpose of making a hole or sawing a slit in the object in which 
the eggs are placed and in guiding the eggs into the hole thus made. In 
one group which has apparently changed its habits and no longer needs 
to make holes for egg laying, the ovipositor being unnecessary for this 
purpose, has been transformed into a sting. 

A pair of many-segmented, antenna-lik« structures, sometimes short, 
sometimes long may occur at the end of the abdomen, and these are 
called cerci. They probably serve as organs of touch, and possibly also 
of smell in some cases. 



CHAPTER III 



THE INSECT: ITS INTERNAL STRUCTURE 



Few of the internal structures of insects are of any great importance 
from the standpoint of control methods, but some knowledge of them 
and their arrangement is desirable. 

Digestive Organs (Fig. 22). — The alimentary canal extends from the 
mouth through about the center of the body to the anus at the hinder 
end. In those insects whose food is most concentrated (Fig. 23), it is 
in its simplest form and is but little if any longer than the body. In 
those which feed on less concentrated food (Fig. 24), the necessity for a 
greater digestive and absorptive surface has resulted in an increase 
of its length and the accommodation of this within the body by the 
production of loops and coils. 




Fig. 22. 



-Diagrammatic longitudinal section of an insect to show the arrangement of the 
internal organs. {After Berlcse.) 



In the embryo the alimentary canal forms as three separate sections 
which connect later. One of these is an ingrowth from the surface where 
the mouth is to be; another and similar ingrowth 'occurs where the anus 
forms; and a third forming earlier than the other two, arises as two 
masses of cells, one near each end of the embryo, which move inward 
and toward each other, unite, and surround the yolk. Later, when this 
has been absorbed, a space is left with which the two ingrowths already 
mentioned connect, the hollow centers of all three joining to form the 
tube through which the food travels. The ingrowth from the mouth is 
usually called the fore-intestine, the central portion the mid-intestine, 
and the ingrowth from the anus the hind-intestine. The first and last 

15 



16 



APPLIED ENTOMOLOGY 



of these begin to grow inward from the surface of the body after that 
surface has begun the formation of its chitinous exo-skeleton, and 
accordingly also have this power, and line the inside of the parts of the 
canal which they form, with chitin. In that portion of the canal termed 
the mid-intestine, however, this power does not appear to be present, and 
the mid-intestine is without this lining. 




Fig. 23. — Alimentary canal of a Carnivorous Beetle, ad, anal glands; cd, stomach; 
ed, hind intestine; in. crop; k, head and mouth parts; a?, CBSophagus; pv, proventriculus; 
r, rectum; rm, malpighian tulies. {Modified from Lamj's Lehrhuch.) 



The mid-intestine forms the stomach of the adult insect; the 
fore-intestine forms those parts of the alimentary canal from the mouth 
to the stomach; and the hind-intestine those from the stomach 
to the anus.. Each of these sections may sometimes have portions 
differing in structure, producing a greater or lesser number of subdivisions. 
Thus the fore-intestine, by differences of structure, may sometimes con- 
sist of a mouth cavity, oesophagus, crop and proventriculus : the stomach 
may develop side pouches or gastric caeca; and the hind-intestine is often 
separable by differences of structure into an ileum, colon and rectum. 

Lined as these parts are by chitin which often bears rough, tooth-like 
projections and spines, some persons have suggested that in insects where 
these structures are present in the fore-intestine, the food is masticated 
more thoroughly and mixed with digestive juices before it reaches the 
stomach. In the stomach digestion is probably completed and absorp- 
tion at least begun, but the length of the hind-intestine in many insects 



THE INSECT: ITS INTERNAL STRUCTURE 



17 



suggests the idea that absorption in those cases has not been completed 
when the food leaves the stomach but continues in the hind-intestine. 
Opening into the mouth is a tube leading to the saUvary glands, which 
generally lie in the front of the thorax and appear to have a similar func- 
tion to those in man. In some cases other glands for different purposes 
are also present in the head or front of the thorax and open into the 
mouth. 




Fig. 24. — Internal anatomy of the Honey Bee showing alimentary canal, tracheal and 
nervous systems, ce, compound eye; hi, hind intestine; hs, honey sac; It, lateral trachea 
(enlarged); mt, malpighian tubes; rg, rectal glands; s, stomach; sp, spiracles. (Modified 
from Leuckart's Wandtafchi.) 

Some of the poisons used in control measures are swallowed by the 
insect, passing to the stomach and there are dissolved by the digestive 
juices. Thus dissolved, they set up inflammation of the stomach walls 
and finally cause death. Poisons acting in this way are called "stomach 
poisons." 

Breathing Organs. — Respiration in insects is accomphshed by a 
method which is nearly unique. The oxygen needed, instead of being 



18 



APPLIED ENTOMOLOGY 



drawn into lungs and there being taken up by the blood and carried to 
the parts of the body where it is needed, as in man, is carried directly 
to those parts by a system of air tubes which open along the sides of 
the body (Fig. 25). Here the air enters the tubes and proceeds through 
them to where it is utilized. The openings by which the air enters are 

called spiracles, and these occur in pairs 
on some of the thoracic and most of the 
abdominal segments, varying somewhat 
in number and in position on the seg- 
ment in different insects. The spiracles 
often have valves by which they can be 
more or less completely closed at will. 

Each spiracle opens into a short tube 
or trachea which, with the others of 
that side, soon joins a similar tube run- 
ning along the side of the body and 
quite close to its surface. From these 
longitudinal tracheae, branches pass off 
in various directions, and in turn branch 
again and again until every part of the 
body is reached by its air supply. The 
tracheae frequently enlarge here and 
there, forming so-called air sacs. 

The tracheae are lined by chitin con- 
nected with that of the surface of the 
body. In these tubes, however, it is 
formed with spiral thickenings which act 
like a spring, keeping the tracheae open 
when not under pressure. There is 
probably considerable pressure on them 
in different places by the movements of 
various parts of the body in walking 
and other activities, as well as by regular 
respiratory movements, and the resulting 
temporary variations in diameter aid in 
the circulation of air in these tubes. 
Not only are the tracheae of use in carrying oxygen to all parts of the 
body, but they also receive the carbon dioxid gas produced by the activi- 
ties of the cells and permit it to escape through the spiracles from the 
body, thus performing both of the functions which the blood, so far as 
gases are concerned, accomplishes in man. Blood then, in insects, does 
not (except in a few cases perhaps) have a respiratory function. 

The destruction of insects by fumigation is accomplished by the sub- 
stitution of a gas destructive to life, for the air, and this gas enters the 




Fig. 25. — Diagram showing ar- 
rangement of the main tracheal tubes 
in an insect, a, antenna; b, brain; 
I, leg; 71, nerve cord; p, palpus; s, 
spiracle; st, branch from main lateral 
trunk, t, to spiracle; v, ventral branch; 
vs, visceral branch. {After Kolbe, 
from Folsom.) 



THE INSECT: ITS INTERNAL STRUCTURE 19 

spiracles and follows along the tracheae to the living tissues, which take 
it in place of the oxygen usually received in this way, and are killed. 

It was formerly supposed that certain materials called contact in- 
secticides which kill insects by contact with their bodies, caused death 
by entering the spiracles and closing them up, thus producing suffocation. 
"This has now been proved to be incorrect. 

Insects which in their early stages live in water, cannot of course 
Ijreathe air into their bodies through spiracles during that period of their 
lives. These are closed in such cases and the animal obtains air usually 
through special structures called tracheal gills. These will be described 
in connection with the insects which possess them. In a few small 
water-inhabiting forms, the chitin covering the surface of the body is so 
thin that oxygen present in the water can pass directly through it into 
the body and to the parts there which need it, and carbon dioxid passes 
in the reverse direction. 

Circulatory Organs. — Insects have only an incomplete system of blood vessels. 
A tube lies in the middle of the body close beneath the back, beginning near the 
hinder end of the animal and extending forward into the head (Fig. 26). In the 
abdomen this tube is constricted, forming chambers, and the chambered portion 
is called the heart. There is a pair of openings on the sides of each chamber 
through which blood can enter, and valves there which prevent its going out 
again. The walls of the heart contain muscles and these contract one after the 
other, forming a sort of wave of contraction which begins at the hinder end and 
travels forward. Blood in the heart, being unable because of the valves, to pass 
out at the sides, is pressed forward by this contraction wave, and at the front end 
of the heart finds itself in a tube without chambers or valves, called the aorta, 
through which it is led to the head where the aorta may divide into a few short 
branches or may be unbranched. In either case, at this point the blood pours 
out of it into the body, the system of blood vessels coming to an end. There is 
now no definite and particular path for the blood to follow, but it would, in theory 
at least, remain near where it escaped from the aorta, or gradually pass into any 
spaces it might find unoccupied between the different structures in the head. 
With each heart-beat, however, more blood is poured out of the aorta, increasing 
the pressure upon that already in the head. It therefore is gradually forced 
backward and to other parts of the body, each particle probably taking the path 
where there is least resistance to its passage. In this way a general backward 
direction is given to the flow. 

As it approaches the heart, another influence appears. During each contrac- 
tion of the heart, it occupies less space, which leads to less than normal pressure 
near it, and blood close by naturally flows closer to it. Upon its expansion again 
and the opening of its valves, the direction of least resistance is now through the 
valves and into the heart. 

As the blood passes back through the body, a given particle may at one circuit 
go over certain organs and at the next, over entirely different ones. All the 
internal organs, however, have their surfaces bathed by blood and this as it 
passes over the stomach or other parts of the alimentary canal will pick up any 



20 APPLIED ENTOMOLOGY 

food which having been digested has passed through the canal walls. Likewise 
in passing over any organ needing this food, it is given up to those organs. The 
blood therefore serves as a distributor of food from the place where it is digested 
to all the parts which need it. 

We have already seen that the living parts of the body — the cells — need 
oxygen, and as the result of their activities give off carbon dioxid gas, but that 
this exchange is accomplished by the aid of the trachesB. In a somewhat parallel 
way, the cells which need food obtain it from the blood. The cells by their 




Fig. 26.- — Diagram showing by the direction of the arrows the general course of the blood 
flow in a Dragon fly nymph, a, aorta; h, heart. {Modified from Kolbe.) 

activities produce not only carbonic acid gas but also waste material nitrogenous 
in nature which must be removed like ed\ wastes, from the body. This nitroge- 
nous waste is picked up at the cells by the blood and carried along , perhaps for 
some time before a place to dispose of it can be found. Sooner or later, however, 
a particle of blood containing this waste material will wash over certain structures 
called Malpighian tubes, to be described in the next section, and the cells which 
form these tubes have the power to collect this waste material from the blood as 
it flows over them, thus purifying it. 

The blood itself is usually a colorless (though sometimes yellowish, reddish or 
greenish) fluid, in which are corpuscles resembling the white corpuscles of human 
blood. It appears to serve to carry food to the tissues, and waste matter from 
them, and therefore has no need of structures in it like the red blood corpuscles 
of man, the work of which in insects is done bj^ the trachea?. 



THE INSECT: ITS INTERNAL STRUCTURE 



21 



Excretory Organs. — The organs which ehminate the nitrogenous wastes 
from the body and correspond in function to the human kidneys, are 
known as Malpighian tubes. These are bhnd-ended tubes, the walls 
of which consist of a single layer of cells surrounding a central channel 
which at one end opens into the hind-intestine, usually near its front, 
just behind the stomach (Fig. 27). When blood containing nitrogenous 
waste matter washes over the outer surface of a Malpighian tube, the 
cells of which it is composed have the power of taking this matter out of 
the blood into their own substance and passing it through themselves into 
the channel between them, down which it moves 
until it enters the mid-intestine, from which it 
is finally expelled at the anus. 

The Malpighian tubes may be few or many; 
long or short (see Figs. 22, 23, 24). They show 
a tendency to collect in groups and to unite near 
the hind-intestine, so that their outlets into this 
are much fewer than the number of tubes. It 
seems possible that a certain amount of poison 
entering the body by way of the stomach can 
be eliminated by the Malpighian tubes, which 
may explain the varying degree of resistance to 
such poisons by different insects. 




Fig. 27. — Portion of the 
Malpighian tube of a fly, 
greatly enlarged, k, cell 
nucleus; I, lumen of the 
central canal; ir, tracheae. 
(Modified from Gcgenbanr.) 



Nervous System. — The nervous system of insects 
is located along the middle line of the body quite 
near its under surface (Fig. 22). As in animals 
generally, it is composed of cells and fibres. The 
former are for the most part gathered together in 
clusters which are called ganglia, and from each of 
the cells in a ganglion, one or more nerve fibres 
pass out, either to connect with some other nerve 

cell or with some structure of the body. The larger nerves are really bundles 
of these fibres running side by side like the wires of a telephone cable. 

Apparently each segment of the insect body once had a nerve ganglion, liut 
with the fusion of the segments, many of these have also fused, reducing the 
separate ganglia in adult insects to a smaller number, which varies in different 
kinds. This fusion has been produced by the hinder ganglia moving forward until 
in some cases none are found in the abdomen. Different degrees of this are 
shown in Fig. 28. 

Each ganghon is connected to the one in front and the one behind by one or 
two bundles of nerve fibres which are called commissures. Each consists of 
numerous fibres and these taken together form the means of communication 
between the different parts of the system. 

In the head, in front of or above the oesophagus, is the largest ganglion of the 
body, called the brain, produced by the fusion of several ganglia. In addition to 
its two commissures, which connect it with the ganglion next behind, it has nerves 
which lead to the ej^es, to the antennae and to other parts of the front of the head. 



22 



APPLIED ENTOMOLOGY 



Below or behind the oesophagus is a second ganglion, also in the head, called 
from its position the suboesophageal ganglion. As the esophagus lies directly 
between this and the brain, the commissures connecting the two do not lie close 
together, but separate far enough to permit the oesophagus to pass between them. 
The suboesophageal ganglion besides being connected with the brain in front, 
and the first thoracic ganglion behind it, by commissures, sends nerves to the 
mouth parts and other nearby regions of the head. 




Fig. 28. — Diagram showing various degrees of concentration forward of four species of 
flies. A, of Chironomus plumosns, little concentrated; B, Empis stercorea; C, Tahanus 
bovinus; D, Sarcophaga carnaria, most concentrated. (After Brandt, from Lang's Lehrbuch .) 

The thoracic ganglia may be more or less separate or fused and may have fewer 
or more of the abdominal ganglia added. Commissures, however, connect all 
separate gangha, and these also send out nerves to all the parts of the segments to 
which they belong, no matter what their final location may be. In this way, the 
wings, legs, muscles and other parts receive their nerve supply. A small "sympa- 
thetic nervous system" also present, appears to be concerned chiefly with the 
nerve supply of the alimentary canal and tracheae. 

Sense Organs. — All the more evident senses possessed by man appear to be 
present in insects, but not in all cases in the same individual. Thus some cave- 
inhabiting insects have no eyes. It is at least probable that insects may have 
other senses not possessed by man. 

Reproductive Organs. — Insects are of distinct sexes, male and female. 
In many cases, however, individuals occur, incapable of reproduction, 
their sexual organs not having become fully developed, and such insects 
may be termed neuters. Most of these appear to be really undeveloped 
females, though undeveloped males are also known. They are found in 
colonial insects where -division of labor occurs, as in the honey bee, ants, 
termites, etc., and are known according to their duties, as workers, soldiers. 



THE INSECT: ITS INTERNAL STRUCTURE 



23 



or by other names. Conventional signs for the various forms of insects 
as a convenience, are : cfniale; 9 female; 9 worker. 

In the female (Fig 29) the eggs are produced n a pair of ovaries located in 
the upper front part of the abdomen. Each is a cluster of ovarian tubes whose 
walls are cells. Some of these cells grow and separate from the others to lie in the 
central cavity of the tube and then pass downward, growing till they reach its 
hinder end, which connects with the similar ends of all the ovarian tubes of that 
side to form a single tube called the oviduct. This extends downward and back- 




FiG. 29. Fig. 30, 

Fig. 29. — Female reproductive organs of Honey Bee {Apis mellifera L.) ; ay, acce.ssory 

gland; o, ovaries; od, oviduct; pg, poison gland; r, rectum, cut off and end bent back; sr, 

seminal receptacle; v, vagina. {Modified from LeuckarVs Wandtafeln.) 

Fig. 30. — Male reproductive organs of Honey Bee {Apis Mellifera L.) ; ag, accessory 

gland; ed, ejaculatory duct; s, spermaries; vd, vasa deferentia. {Modified from Leuckart's 

Wandtafeln.) 

ward around the side of the alimentary canal, below which it joins with a similar 
oviduct from the other side of the body to form a single duct, the vagina, which 
lies below the ahmentary canal, and extends backward to its outer opening which 
is located in most cases, in front of the next to the last abdominal segment. 
Surrounding this opening may be external structures (an ovipositor) for the pur- 
pose of together making holes in some object (the ground, wood, etc.) in which 
to deposit the eggs. A side pouch (seminal receptacle) connected with the vagina 
is for the storage of the sperms wh ch fertilize the eggs ; a gland producing material 
which forms the egg shell and is known as the shell gland, also opens into this 
portion, and other glands similarly connected with the vagina, may also be 
present. 



24 APPLIED ENTOMOLOGY 

In the male (Fig. 30) the arrangement of the organs closely corresponds to that 
in the female. A pair of spermaries or testes is present in the upper front part 
of the abdomen, each consisting of a rather closely-coiled mass of tubes, in which 
the sperms are produced. The tubes on each side unite to form a single tube, 
the vas deferens. These differ from the oviduct usually, in being much longer 
and coiled or twisted. They pass downward and backward, however, and unite 
on the middle line of the body below the alimentary canal, forming a single tube, 
the ejaculatory duct, corresponding to the vagina in position, which leads back- 
ward to an opening in front of the last segment. An enlarged portion of the vas 
deferens is often present, for the temporary storage of the sperms, and is termed 
the seminal vesicle. Accessory pouches opening into the ejaculatory duct appear 
to be in part at least, for the production of mucus and secretions to mix with the 
seminal fluid. 



CHAPTER IV 
THE DEVELOPMENT OF INSECTS 

Most insects lay eggs which hatch after a longer or shorter time into 
the young. In some cases the egg appears to be retained within the 
body of the parent until after it has hatched, and then the young are 
produced in a stage able to move about. Insects in which this is true 
are termed viviparous, the others being oviparous. 

Insect eggs are usually very small; vary greatly in form, and may be 
laid singly or in clusters (Fig. 31). They are covered by a chitinous 
shell, the chorion, which often bears markings in the form of ridges. 






Fig. .31. — Eggs of various insects. A, butterfly; B, house fly; C, chalcid (Brucho- 
phagus); D, butterfly; E, midge; F, bug {Triphlej>s); G, bug (Podisus); H, Pomace fly. 
All much enlarged. (From Folsom.) 

reticulations, etc., and frequently they are also colored. At one place on 
the surface is a minute opening or group of openings through the shell, 
called the micropyle, believed to be for the entrance of the fertilizing 
sperm. The length of time spent in the egg differs in different insects 
from a few hours to many months, and in some cases the eggs do not 
hatch until the second season after they are laid. 

In hatching, the shell breaks and out of it crawls the young insect, in 
the majority of cases quite unlike the adult it is to become. In order to 
reach maturity it must now grow, and undergo changes in structure and 
appearance. These together are expressed by saying that most insects 
in order to become adult undergo a metamorphosis. In some of the 
simpler insects, a few changes and growth only, are needed to make them 
mature, and these are therefore usually grouped together as the Ameta- 
bola, or insects having practically no metamorphosis. 

25 



26 APPLIED ENTOMOLOGY 

The remaining insects, from this standpoint, form two groups : those 
which on hatching show some resemblance to the adults and reach matu- 
rity by a certain series of changes; and those which on hatching are 
totally unlike the adults and attain that condition in a different way. 
These groups are known as the Hemimetabola or Heterometabola, and 
the Holometabola respectively, these names suggesting the amount of 
metamorphosis required for members of each group to become adult. 

A member of the group Ametabola, upon hatching, will begin to 
feed and grow. Growth, however, is restricted because the insect is 
enclosed by chitin which, while elastic to some extent, at least at its 
thinner portions, has its limitations in this regard. In some cases the 
insect is able to reach its adult size within the chitin, but in other cases 
this proves impossible, and a process called molting takes place. This is 
begun by pouring out of fluid by the outside layer of living cells, the 
hypodermis, between it and the chitin, separating the two. Next a 
split in the chitin appears somewhere, usually along the back, and the 
insect crawls out of its skin, i.e., molts. It is now soft and unrestricted by 
an outer shell and grows rapidly. A new chitinous shell begins to appear 
and is completed in a short time (within a day or so) and thereafter only 
such growth is possible as the elasticity of the new shell will permit. 

In most of the Ametabola, molting as thus described is not usual, 
the shell being sufficiently thin to stretch the amount needed for growth 
to adult size, though sometimes two or even three molts may occur. 
In both cases, however, the reproductive organs appear not to be mature 
at the time of hatching, and only gradually become so during the period 
following. In a few cases molting seems to occur at intervals throughout 
hfe. 

In the Hemimetabola (or Heterometabola) the young insect on es- 
caping from the egg, though resembling its parent to some extent, 
must nevertheless undergo many changes in structure and a considerable 
increase in size as well, before reaching maturity. Thus a young short- 
horned grasshopper, on hatching, will need to grow to be about ten times 
as long before becoming adult; it is without wings, which will need to be 
developed; its reproductive organs are not mature and must become so, 
and other differences occur. All of these must be transformed into their 
condition in the adult, and to accomplish this, energy is necessary. In 
the egg the energy for development had been provided by the yolk: 
after hatching the young insect must provide it by gathering food. 

The young insect therefore, soon after hatching seeks for food, and 
having found it begins feeding. The nourishment thus obtained results 
in growth so far as this is possible within a shell which is tightly fitting 
and only to some degree elastic. When no fuj-ther growth in this way 
can occur and the body has stored within it all the materials needed for a 
greater increase in size, it proceeds to molt in the manner already de- 



THE DEVELOPMENT OF INSECTS 27 

scribed for the Ametabola. On escaping from its old skin or shell, how- 
ever, besides a rapid increase in size, changes of structure also occur, 
so that a difference in appearance now becomes evident. These changes 
must be produced quickly, as the hypodermal cells of these parts, as 
well as of all the surface, are producing a new chitinous skin, and when 
this has once hardened, no further changes and little further growth are 
possible. Molting then, marks the beginning of a brief period — a day, 
more or less — of increase in size and of changes in appearance, these last 
all being in the direction of making the young insect more nearly like the 
adult it is to become. When the new shell has become hardened the 
insect resumes its feeding. 

After another feeding period the young insect is again confronted 
with the same difficulties as before, and it meets them in the same way, 
by molting, and immediately thereafter, before its new shell has hardened 
it seizes the opportunity to grow and change its appearance further. 
Finally, after some molt, full adult size for the insect is attained and all 
its organs have also fully developed and matured, producing the adult 
insect itself. 

Thus the young insect becomes an adult by alternating periods of 
feeding, with brief periods of molting, following which growth and change 
take place, the total of which produces the adult. 

The number of molts and consequent opportunities for change wliich 
occur, varies in different Hemimetabola. There may be only two or 
three in some kinds: five is perhaps the average number though more 
are not uncommon, and 21 are known to occur in one species. 

Certain names for these different conditions are convenient for use. 

The feeding periods between the molts (or ecdyses) are called instars, 
so that the progress of an insect from hatching to adult is by an 
alternation of instars and molts. The insect itself, from hatching until 
maturity is generally called a nymph. Figure 32 shows the changes in 
size and appearance of a grasshopper after each molt. 

With the remaining group of insects, the Holometabola, while there 
is a little similarity in the metamorphosis to that in the Hemimetabola, 
there are also many differences. 

When a young Holometabolous insect hatches, it in no way resembles 
its adult. A caterpillar is totally different in appearance from the butter- 
fly it finally becomes : the white grub in the earth is in no way suggestive 
of the June bug (May beetle) into which it transforms. Nevertheless 
it has to meet the same problems of growth and transformation to the 
adult condition as do the Hemimetabola, and uses the same means for 
accomplishing the needed results, viz., the utilization of the energy 
derived from its food. 

Accordingly, upon hatching, in the Holometabola, a feeding period or 
instar comes first, followed by a molt and growth. At this point the 



28 



APPLIED ENTOMOLOGY 



story of the metamorphosis differs from that of the Hemimetabola, for 
after the molt no change in appearance to make the young insect more 
nearly like the adult takes place. It may be different in some regards 
besides size, from what it was before the molt, but these differences do not 
increase its resemblance to what it finally becomes. This holds through- 
out the feeding period of its existence, so that after three, four or more 
molts, a caterpillar is still a caterpilar, a grub is still a grub, and this is 
equally true for all Holometabolous insects. Within the insect during 
this period, however, changes not perceptible on the surface are taking 
place, by the construction of portions of the adult which are forming as 




Fig. 32. — Incomplete metamorphosis of a Grasshopper, a, first iiymphal instar; 
b, second instar; c, third instar showing beginning of wings; d, fourth instar; e, fifth instar; 
/, adult. Figures not drawn to same scale. (Modified from Packard's Text-book 
of Entomology by ■perm,ission of the MacMillan Company, Publishers.) 

buds or ingrowths from various parts of the body, and are termed imagi- 
nal buds (from "imago," the adult). They are closely compacted and 
many at least are infolded somewhat like buds, becoming finally ready to 
open when the proper time comes. And during its feeding instars, the 
larva, as the young insect in the Holometabola is called, is not only 
storing energy from its food for its growth at each molt, but also to carry 
it on through a period yet to be described, during which it must transform 
into the adult condition while unable to feed and obtain the energy needed 
for this purpose. 

After a varying number of feeding instars and molts, the young 
insect or larva has grown sufficiently and has stored within it energy 
enough to carry it through the remainder of its changes, and internally 
the essential parts for the adult condition have been formed as far as 



THE DEVELOPMENT OF INSECTS 29 

possible under existing conditions. As the next change will produce an 
animal practically helpless in most cases, and unable to protect itself 
from its enemies, its next step is to find as much protection as possible. 
Accordingly, the full-grown larva usually, though not always, leaves the 
place where it has been feeding and elsewhere prepares for its next 
change. Many larvae begin this by spinning around themselves a 
thread of silk, produced by glands within the body and opening to the 
surface on the lower lip. This thread is spun backward and forward and 
around the body until it sometimes forms a complete outer covering, 
entirely concealing the larva within, from view. This case or cocoon 
appears to be protective in its function. 

Some larvae go under ground for this change. Here a cocoon, as such, 
seems unnecessary, but after digging into the earth a few inches, the 
insect forms a little earthen chamber or cell in which to lie, and generally 
lines this more or less densely with silk, probably to keep the earthen walls 
from falling in and crushing it. A larva transforming in tunnels in wood 
where it has fed, may make a partial cocoon with more or less of the 
chewed-wood fragments mixed in. One staying above ground but not 
in tunnnels or otherwise protected, will spin more or less of a cocoon 
as already described. 

The completeness of the cocoon, however, varies greatly with differ- 
ent insects. Instead of being a thick, dense wrapping which entirely 
conceals the insect, it may be so scanty that the animal within can bo 
seen to some extent. In other cases it is merely a sort of network, in no 
degree giving concealment; and in still others, a few scattered threads to 
hold the insect in place are all that represent it. Sometimes hairs from 
the body of the larva, held together by silk, form most of the cocoon, 
and in the case of butterflies, only threads enough to attach the hinder 
end of the body at the place where it is to transform, and to form a 
supporting loop around its middle, the ends of the loop also being fastened 
to what it rests on, are produced. In some flies the larva shrinks within 
its larval skin and transforms, this skin, now called a puparium, function- 
ing like a cocoon (see Fig. 33c). 

The reason for such variations in a structure presumably formed for 
the purpose of protection, can only be guessed at. Possibly in the course 
of generations, some insects found less need of this than others and gradu- 
ally reduced it, thereby saving the vital energy so much needed for trans- 
formation, which would otherwise be expended in cocoon making. 

Whether the larva forms a dense or scanty cocoon, or none whatever, 
the next step in the process is a molt. When the insect escapes from this 
skin, however, a great change in its appearance is evident, and it is now 
called a pupa (Fig. 33a and h). In a general way it may be said that it 
has at this one molt changed more than half way to its adult condition. 
This is due in part at least to the unfolding of the imaginal buds already 



30 



APPLIED ENTOMOLOGY 



referred to, which contribute largely to form the new surface of the body 
in which head, thorax and abdomen are evident, as are also the antennae, 
legs, stubs of wings and other adult structures. Many of the internal 
organs of the larva though, were necessary for use till the last moment 
before it became a pupa. Then too, the arrangement of the muscles, 
in the larva, would not be that needed by the adult. Accordingly, most 
of the internal organs now gradually break down, losing all their earlier 
form and structure, and new ones to meet the needs of the adult are con- 
structed to take their place. 




Fig. .33. — Different types of pupation, a, pupa obtecta of a moth; b, pupa libera of a beetle; 
c, puparium of a fly. a and h about natural size; c much enlarged. (Original.) 

During this breaking down and the reconstruction period, the pupa 
is practically helpless in most cases, hence generally the need for the 
protecting cocoon or earthen cell it constructs. 

When the structure of the adult insect has been completed, another 
molt takes place, the pupa skin splitting and setting free the insect. If 
it was enclosed in a cocoon it now produces a fluid which sufficiently 
softens the silken threads so that it can push its way out and it escapes or 
"emerges." It is now soft, its wings are only partly expanded, as in 
most cases there would be no room for full-sized wings in a pupa, and 
because of its reconstruction there is considerable waste matter in its 
body. The insect crawls upon whatever it may find to hold on to, expels 
the waste matter, and its wings begin to grow rapidly. Drying out also 
takes place and in a short time (a few hours) the adult thus produced is 
in every way fully matured. 

To summarize the differences in metamorphosis of the three groups it 
may be said that in the Ametabola the insect hatches from the egg prac- 
tically in an adult condition, i.e., there is little or no metamorphosis. In 
the Hemimetabola the insect hatches from the egg in a form somewhat 
resembling the adult but much smaller. It becomes adult by alternating 



THE DEVELOPMENT OF INSECTS 31 

periods of feeding with molts, at which times growth and changes bringing 
it nearer to the adult occur, the last molt completing the growth and adult 
structure. In this life history we have a change, but as there was a 
resemblance to the adult from the start, the change to it (metamorphosis) 
is only an incomplete or partial one. 

In the Holometabola the insect hatches from the egg in a form totally 
unlike the adult, and while feeding periods followed by molts and growth 
give increase in size, no external evidence of any changes making the 
insect more like the adult can be found. These changes are largely made 
after the end of the feeding and growing periods during a pupa (generally 
quiet) stage, in which the breaking down of the larval, and construction 
of the adult structures is completed. The difference between the larva 
on hatching and the adult is so great that an entire change (complete 
metamorphosis) takes place. 

It should be evident from the foregoing that when the adult condition 
is once reached, little if any growth is possible (except in rare cases) 
and that the belief so common, that ''big flies grow from little flies," 
is without any basis of fact. 

The nymphs of the Hemimetabola appear not to have attracted 
sufficient attention to have received any special common names. In 
the Holometabola the larvae of various groups differ greatly in appear- 
ance ; many are large and noticeable and some of them have, as a result, 
received special names. Larvae of butterflies and moths are commonly 
called caterpillars; those of beetles are usually called grubs; those of 
flies are called maggots. Larvae found boring in wood, however, whether 
they will become moths, beetles or other insects, are uniformly called 
borers. 

In the Hemimetabola then, the stages of life are: egg, nymph, adult; 
in the Holometabola they are: egg, larva, pupa, adult. Whether "or not 
the pupa is enclosed by a cocoon depends upon circumstances. 



CHAPTER V 
LOSSES CAUSED BY INSECTS : NATURE'S CONTROL METHODS 

To ascertain how much man loses by the attacks of injurious insects 
is a difficult task. The destruction, either partial or entire, of his crops 
both growing and in storage; of household goods and of food; of our 
forests and of the wood cut therefrom; injuries to our domestic animals 
and their products: these and other injuries can be more or less accurately- 
estimated. But when we consider the attacks upon man by disease- 
carrying insects, resulting in loss of time from productive labor, or even 
by death, and the actual costs connected with illness, the problem 
becomes extremely complicated, and to determine how much financial 
loss this countrj^ suffers from insects is a matter for the economist as 
much as the entomologist. 

Much of this loss W3 fail to appreciate, never having had a season 
free from the attacks of insects which might serve as a standard for 
comparison. If we could once have such a year entirely insect free, 
however, the difference would at once force itself upon our notice. 

Crop Losses. — Careful studies of the crops injured by insects have 
now extended over quite a term of years, and the general conclusion 
rsached is that in an average year with no unusual attack, a crop will 
generally produce only about nine-tenths as much as would probably 
have been the case had insects not been present. When an outbreak 
occurs, this will decrease production below that point, and instances 
are fai* too frequent where for a single crop of some kind, production has 
been only 20 or 30 per cent of the normal, and many cases are on record 
where in some localities the destruction has been complete. 

This estimate covers field crops; destruction of forests and forest 
products; attacks on domestic animals and their products; articles in 
storage; on shade trees, shrubs and ornamental plants; on farm wood 
lots which are not included with the forests; on household goods and foods. 
With fruit and truck crops the destruction and injury is believed to be 
more than one-tenth generally. 

Health Losses. — A number of serious diseases of man are due to 
insects which serve as carriers of the disease-producing organisms. 
Among these are malaria, the typhoid, typhus and yellow fevers, and the 
bubonic plague, besides others of less importance. Illness with any 
of these diseases means that the patient is not only unable to work but 
is an actual cause of outlay for nursing, treatment, and possibly death 
expenses also. With hundreds of thousands of illnesses from these 

32 



LOSSES CAUSED BY INSECTS. NATURE'S CONTROL METHODS 33 

diseases each year, the loss of time from productive labor is, of course, 
very large, and the country is that much poorer than it should be. Death 
puts an end to any further production by those concerned, and here 
also is a loss to the country. It has been estimated that the loss of 
labor by sickness and death, caused by malaria alone, is at bast $100,- 
000,000, and by all insect-borne diseases is over $350,000,000 each year 
in the United States. 

In addition, there are many places in this country where the soil 
is rich and would pay well if cultivated, but where man cannot live 
under existing conditions because of the presence there of insects and 
the diseases they carry. 

Difficulties in Estimating Losses. — To fix a monetary value for all 
this destruction and injury, however, is a difficult problem, so many fac- 
tors enter into it. It cannot be denied that insect attacks result in a 
direct reduction of wealth to the country as a whole; that whatever food 
material has been consumed by insects is not available for consumption 
by the people, is self-evident; and that if on account of a resulting scarcity 
of any food the consumer pays more for it, he is thereby paying toward 
the cost of the ravages by the insects. The producer of this food though, 
may because of the reduced amount available, be getting as much or even 
more than he would have received had insects not destroyed any of it. In 
other words, while the destruction of any crop caused by insects is cer- 
tainly a loss to the nation as a whole, those fortunate individuals who suc- 
ceed in raising that crop may receive as much or more for the amount they 
did produce than would otherwise have been the case. On the other hand 
the man who starts to raise such a crop and loses a large percentage of it 
by insect ravages, may not have a sufficient amount left to repay him 
even at the higher prices, for his expenses. 

It is evident then, that insect ravages while meaning a loss to the 
country as a whole, may also mean either a loss to producers, a normal 
profit because of a higher price on what part of the crop they have been 
able to save, or even a better profit, due to higher prices than could other- 
wise have been obtained. 

No crop producer can as yet foretell whether he in any given year will 
be one who will lose, receive a normal return, or do better than usual on 
any of his crops. He can only be prepared for insect attacks if they come, 
and save all he can by proper methods of protection and repression, know- 
ing that the vast majority of the people will do little or nothing in this 
line and that in consequence he will be among those losing least; will have 
proportionally more to sell, and that he will therefore receive the benefit 
of any higher prices coming from a reduced production. 

Against what he will gain in this way must be offset the cost of his 
protective and control measures. If these are too expensive he will gain 
nothing, but in most cases their cost is small as compared with the value 



34 APPLIED ENTOMOLOGY 

of the product saved, and such measures used with judgment represent 
one of the cheapest and most successful forms of crop insurance. 

It is certain that the time will never come when protection of crops 
from insect ravages will ever be so universal and successful that to produce 
crops will not pay, for with our increasing industrial population to be fed 
the demand is more likely increasingly to exceed the supply, even though 
every crop producer should finally come to the protection of what he raises, 
from insects. At present the farmer who adopts modern methods against 
insect injuries is certain in any term of years to raise more and to sell at 
higher prices than one who trusts to chance or "luck" in this phase of his 
industry. 

Figures on Losses. — From the above it becomes evident that no 
accurate figures as to the losses caused by insects can be given. We can 
only recognize that everything produced which is destroyed by these pests 
is thereby lost to the country as a whole, even though some individuals 
may profit. To value this destruction we have only the prices for which 
crops sell, as a criterion, and the point has already been brought out that 
if the tenth destroyed had been saved, the price of the whole might have 
been no greater than it was for the nine-tenths actually produced. Tak- 
ing this unreliable standard, however, in order to get some slight idea of 
the amount of destruction ordinarily caused by insects, we may bring 
together the following statement, based on the average value of the crops 
for the five years 1913-1917 as given in reports of the United States 
Department of Agriculture and from other sources. 

Field crops $833,660,000 

Animals and their products 431 , 450 , 000 

Forests, forest products and materials in storage 300,000,000 

Loss by human disease and death 350,000,000 

Farm wood lots • 100,000,000 

Extra losses on fruit and truck crops ? 

Shade trees and ornamental shrubs and plants ? 

Household goods and foods ? 

Altogether, if we may accept figures based on the assumption, as has 
been indicated, that if no losses had occurred the value of the whole 
would be at the same rate as the actual price for what was obtained, it is 
safe to estimate the loss in the United States due to injurious insects as 
being not far from two billion dollars each year. How nearly correct this 
is, however, no one can tell, so many factors enter into the problem. 

Causes of Increased Injury. — Losses to crops, forests and other mate- 
rials are increasing, for several reasons. Before the settlement of this 
country there were, of course, native insects attacking the various plants 
growing here. When settlements were established new plants were intro- 
duced by the settlers and grown in greater abundance than if they were 



LOSSES CAUSED BY INSECTS: NATURE'S CONTROL METHODS 35 

wild and scattered. An insect finding in any of these a food acceptable 
to it, would at once also find a more abundant supply, and a rapid multi- 
plication would become possible, resulting in their increase to injurious 
abundance. A second factor has been the introduction of many insects 
from foreign countries. In the United States such forms have sometimes 
entirely failed to maintain themselves. Unfortunately, as has more fre- 
quently happened, they have found all conditions favorable to a rapid 
increase, unchecked by their enemies which in most cases have not also 
been brought to this country with them. A third factor has been that 
with the increasing occupation of this country, much of its wild bird life 
has either been destroyed or has been driven away from the neighborhood 
of man. Many insect feeders among birds, once quite common, must now 
be sought in remote woodlands and thickets, and rarely show themselves 
near settlements. Some kinds have adjusted themselves to the new 
conditions and among these may be mentioned the robin, chipping 
sparrow, blue bird and a few others. But to too great a degree the insec- 
tivorous birds are becoming either fewer in number or afraid to visit the 
settled districts where cats and people are numerous, even though in such 
places the gardens and trees may be thickly populated with insects. 

With modern agricultural methods distinctly favoring a rapid in- 
crease of insects by providing an enormous acreage of a single crop;' with 
an addition to our worst native pests of at least as many more from other 
countries, which have escaped their enemies by coming here; and with 
our birds becoming less effective in their work, it is only natural that losses 
by the attacks of insects should be great and increasing in importance. 

Control by Natural Methods. — In countries undisturbed by man 
and his industries it is probable that destruction or serious injury from 
insect attacks would usually be rather small, particularly in a series 
of years. The saying in Physics that ''Nature abhors a vacuum" 
seems to be paralleled in Biology by the paraphrase, "Nature abhors 
extermination." Accordingly, insects appear to be more or less com- 
pletely held in balance by natural factors, some of which may be briefly 
considered here. 

Plants of various kinds form the food of most of the insects which 
we regard as pests, and in a country entirely under natural conditions, 
plants of any one kind are liable to be more or less scattered, no large 
number being close together. Under such conditions a search for the 
proper food plant is necessary to an insect as a preliminary to egg- 
laying, and in many instances these may be too scarce to provide for all 
the insects. In any case, where the food supply is scanty, an insect 

^ As an example of this, apple orchards containing thousands of trees are now 
common. It is stated that one year in a single valley in California, there were three 
wheat fields each containing over twenty thousand acres. 



36 APPLIED ENTOMOLOGY 

species feeding wholly on that kind of plant will be more rare than where 
its food is abundant. If, on the other hand, there is an abundance of 
the food plant, there is a greater probability of the survival of more of 
the insects. But this brings its disadvantages. Increase in the number 
of the insects will result in more food being needed, and finally this will 
become insufficient and will be followed by the failure of many to find 
food, death resulting. In this way a balance may be finally secured, 
though it will not be permanent, the process being repeated in the 
subsequent years. 

Weather conditions are also a factor in Nature's control. Some 
insects find in a wet season conditions favoring the survival of a large 
proportion of those which appear, while for others such a season produces 
heavy mortality. A severe winter with many and marked fluctuations 
of temperature may put an end to the rapid increase of some species 
which because of preceding favorable winters, has been becoming more 
abundant. Other meteorological factors also enter into the subject of 
insect control. 

Birds and other animals which feed on our insects must also be con- 
sidered in this connection. When insects acceptable to these animals are 
abundant, more will be eaten and in any case many will be destroyed in 
this way. Where insectivorous birds have an abundant food supply 
more will survive, which will result in more individuals to be fed. Thus 
an abundance of insects may lead to a corresponding increase in abun- 
dance of their enemies. 

Parasites and diseases play their part too in this competition. The 
more abundant an insect becomes, the more food is thereby available 
for its parasites, and fewer of these will fail to find an insect to attack. 
Finally the parasites may become so numerous that practically all the 
insects of the kinds they attack will be found and killed. The next 
generation of parasites following this, will, of course, consist of many 
more individuals than the one preceding, but now so many of their 
food insects or ''hosts" have been killed in producing them that there are 
practically none left, and most of these parasites die for lack of food. 
Thus, under these conditions, a sort of "balance of Nature" develops, 
and though the scales may tip first to one side and then to the other, 
this balance is usually preserved if periods of a number of years at least, 
are considered. 

But when man with his many lines of activity appears in the field, 
introducing and raising millions of plants of the same kind in small 
areas, instead of scattering them here and there, thus furnishing enormous 
quantities of food for insects; and when he brings in many pests from 
foreign countries, no matter how unintentionally, which in their new 
home are not beset by the foes present in their native land; and when 



LOSSES CAUSED BY INSECTS: NATURE'S CONTROL METHODS 37 

his manner of life is such as to drive away birds which might be valuable 
aids in his struggle against pests, the situation changes rapidly for the 
worse. 

Those who look on the bright side are confident that in time Nature 
will reestablish a balance, and this is probably true. But Nature works 
in centuries, and man cannot wait so long for results. 

Under these conditions artificial measures as contrasted with natural 
ones must be taken if crops are to be raised, food obtained, and if health 
is to be preserved, and these artificial methods for the control of injurious 
insects need to be known, and the nature of their action understood. 



CHAPTER VI 
ARTIFICIAL METHODS OF CONTROL 

It has been indicated that Nature has methods for the control of any 
continued undue abundance of insects, by a resulting scarcity of food; 
by weather conditions; by insectivorous birds and other animals; by 
parasites and diseases; and probably in other ways also. But it seldom 
pays to wait for the results so obtained, as they generally require a num- 
ber of years for completion, and measures which may be termed artificial, 
inasmuch as they are used by man, also have their value. 

These measures may be divided into two groups, viz., those which 
aim to establish conditions unusually favorable to the plants or un- 
favorable to the insects; and those which attempt either to poison or 
otherwise directly kill the insects. In some cases perhaps, a given treat- 
ment might seem to belong as properly in one of these groups as in the 
other, but in general the line of separation is quite distinct. 

Whatever the method and its effectiveness may be, there is always 
the cost of using it to bear in mind. When this cost is greater than the 
loss would otherwise probably amount to, it is evident that little will be 
gained by treatment, except that in such cases possibly, omitting it for 
this reason one year may result in such an increase of the pest as to pro- 
duce serious results the following season. In other words, treatment 
costing more than the probable loss may sometimes pay as a sort of in- 
surance. In general, though, in every case where insect attack occurs, 
the estimated cost of the treatment should be weighed against the 
probable loss without it, in deciding whether to treat or not. 

GENERAL FARM PRACTICES 

These are chiefly methods for raising crops which distinctly increase 
their vigor and growth or remove conditions favorable to insects. 
Healthy crops, clean culture, the rotation of crops, late or early plowing, 
and the time of planting are the chief farm practices which belong here. 
Special methods for particular cases, directed more with reference to the 
insects than to the handling of the plants, such as hand picking, the use 
of repellents, burning insects, heat, trap lanterns, etc., may also be in- 
cluded here, leaving the measures dealing with insects by the use of poisons 
and by fumigation for later consideration. 

38 



ARTIFICIAL METHODS OF CONTROL 39 

Healthy Crops. — In the majority of cases a vigorous, thoroughly 
healthy plant is not only better able to withstand insect injury but is 
also less liable to attack than one enfeebled or not thriving for any reason. 
Thorough cultivation, the use of fertilizers and the removal or repair of 
injured or diseased parts or plants as soon as these appear, will aid 
greatly in insuring the desired results. 

Clean culture is also an important factor. Weeds not only interfere 
with successful crop growth but may in some cases at least, consume 
plant food in the soil which might otherwise be utilized by the crop, 
thus reducing its vigor, and in addition they provide wintering places 
for many insects. Rubbish left on a field after the harvest often serves 
the same purpose: insects frequently find protection during the winter 
in tall grass too often left surrounding the trunks of fruit trees, and 
many serious pests winter close to the ground in grass fields. Decaying 
fruits and vegetables harbor insects and should be composted. Weeds 
should therefore be killed and burned and the grass kept down in or- 
chards. Burning over grass fields in early spring in the Northern states at 
least, choosing a time when the dead growth is dry enough to burn while 
the living parts of the grass are still so wet as to be uninjured by the heat 
is often a valuable way in which to destroy many pests which winter 
there. Clean culture in all its forms, not forgetting fence-line and road- 
side growth will do much to reduce loss by insects. 

Crop Rotation. — The rotation of crops often has an important bearing 
on insect control. Any crop attacked by a particular species of insect 
should not be followed by another, either of the same kind or by a differ- 
ent one which is also fed upon by that species of insect. How far this 
principle can be carried out in practice, however, is a different matter. 
To break up sod land and plant corn for the first crop is merely to follow a 
mixture of grasses with a single kind of a grass and from the standpoint of 
insect control at least, is unwise. It is the usual practice though, and 
how far it would be wise to depart from it, planting beans, buckwheat or 
perhaps potatoes instead, is a question, though these last-named crops 
would be much more likely to be free from insects. The entire subject 
of crop rotations which are satisfactory from the standpoint of agri- 
culture and are also correct when insect problems are considered, is still 
in a far from settled condition, and needs prolonged investigation. 

Plowing. — Many serious pests winter in the ground. Fall plowing 
after they have formed the cells in which they pupate or winter, as the 
case may be, will break many of these and remove the protection they 
give : eggs laid in the ground will often be buried so deeply that the larvae 
if they hatch in spring will be unable to reach the surface. Similarly, 
thorough cultivation in the summer, where it is possible, besides being 
good for the crop, has an injurious effect on insects there. 

In some cases early fall plowing gives the best results ; in others, late 



40 APPLIED ENTOMOLOGY 

fall is the best time. Sometimes disking with a harrow can be done 
where plowing cannot, and is of value. 

Time of Planting. — This is sometimes of importance as a protection 
against pests. Thus, in general, wheat sown after September 20 will 
escape the attacks of the Hessian fly : early planting will often give 
cotton an opportunity to obtain the greater part of its growth before the 
boll weevil has progressed far in its ravages, particularly if early maturing 
varieties of cotton are planted. It follows from this that a choice of 
the variety to plant is also often of impoi'tance, and insect-resistant 
varieties of our various crop plants and trees should be selected as far as 
any are known, if they are otherwise satisfactory. The " bugless potato," 
while perhaps non-existent, expresses an idea which should be kept in 
mind, and resistant varieties of plants should be watched for and 
preserved. 

Trap Crops. — In some cases trap crops can be made use of to advantage. 
A small patch of kale planted in the fall, or of mustard planted early in 
spring will attract the Harlequin cabbage-bugs as they leave their winter 
quarters, and on these they can be destroyed, as they seem to prefer 
such plants to the young cabbages. Several similar cases are also known 
where trap crops work well. 

Hand Picking. — In some cases, where the pest is large, easily seen, 
or not present in large numbers, hand picking is the easiest method of 
control. Egg clusters are often of such a color, size, or have such notice- 
able features that they are not difficult to find, and the convenience of 
destroying several hundred eggs at a time, as compared with killing the 
same numbar of insects after the eggs have hatched and the young have 
scattered, is evident. Larvae feeding in groups together are also often 
most easily destroyed by hand picking. 

Repellents. — Inert materials, such as air-slaked lime, flour, or even 
fine road dust, thickly spread over plants will, in certain cases, act as 
repellents, driving insects elsewhere to a greater or lesser degree. Car- 
bolic acid, naphthaline, oil of citronella, and other materials having an 
objectionable odor act as repellents to some insects. 

Trap Lanterns. — These have been quite extensively tested, but have 
failed to be as successful as was expected. Though many insects are 
attracted to such lights, the greater number are found to be beneficial, 
while of the injurious kinds a large number have already laid their eggs 
and are therefore no longer of any importance, and most of the serious 
pests are not attracted at all. On the whole it is doubtful if the use of 
trap lanterns ever pays. 

Burning Insects. — Gasoline torches for burning egg clusters, cater- 
pillars, scale insects, etc., on trees, have also been tried, but the time 
necessary to kill the insects in this way is often long enough to injure 
the tree where the blast hits it, and this method must be regarded as at 



ARTIFICIAL METHODS OF CONTROL 41 

least exposing the plant treated, to the risk of greater injury than that 
caused by the insects. 

Heat. — Heat can sometimes be used to advantage for the destruction 
of insects. A temperature of 125°F. is enough, if maintained for 3 or 
4 hr., to kill insects infesting grain, seeds, etc.,- and also almost all house- 
hold pests at least. Where heat can be applied in this way, therefore, it 
is a special method of control of considerable value. 

Miscellaneous Methods. — Borers in trees present particular difficul- 
ties, being so hard to reach, and cutting them out by hand is frequently the 
best control method. Protective coverings over or around plants may 
sometimes be used to advantage, as for example, netting over young 
cucumber and squash plants. Sticky bands placed around the trunks of 
trees keep insects which cannot fly from crawling up to the leaves. 
Pieces of bark or boards on the ground near plants, under which insects 
may crawl for protection at night, as some do, are good traps for such 
insects, if these traps are visited early in the morning and the insects 
destroyed before they scatter again for the day. Burlap bands around 
tree trunks attract many caterpillars as being good hiding places during 
the day. These and numerous other special methods for the control of 
insects are made usb of, many being based on some peculiarity of habits 
of the special pest for which they are used. 

Still other methods will be considered later, in connection with the 
insects against which they are used. 

In order to make proper use of the above methods of Farm Practice, 
a clear understanding of the life and habits of the insect to be controlled, 
must be had. Failure in this might easily lead to doing just the wrong 
thing. 

The control of insects is at the present time very unequally developed 
for different crops. Naturally the insects of those which are most 
valuable have been most carefully studied, those of less importance 
having been given much less attention. Fruit and market-garden crops 
have a high value and the insects which attack them have been carefully 
investigated, though the area they cover is very small as compared with 
the wheat acreage of this country, for example. Trees, bushes or other 
plants, whether growing alone or in rows with cultivated land or grass 
surrounding them are accessible as units on which to work, but a 10-acre 
field of clover, wheat or any other crop, is a totally different proposition. 
The former can be reached in all its parts by a spray or other treatment: 
a wheat plant in the middle of a field may need treatment but to reach 
it would probably cause a greater amount of injury than would be saved 
by the treatment. 

Field crops and particularly grain crops therefore, present distinct 



42 APPLIED ENTOMOLOGY 

problems, and here Economic Entomology and Practical Agriculture 
have failed to work as closely together as should be the case, and our 
present methods for controlling field crop insects are less effective than 
with most others. 

The same, thing is true with our forests. The shade tree can be 
sprayed if that is a desirable treatment, but the spraying of forests even 
if practicable from the standpoint of expense, is frequently impossible 
because of the nature of the ground on which the forest stands, density of 
growth and other factors, and other and more indirect methods of insect 
repression then must be resorted to. 



CHAPTER VII 

INSECTICIDES IN GENERAL: STOMACH POISONS 

Though the farm practices and special methods outhned in the pre- 
ceding chapter are of great importance for the control of insect pests 
in many cases, they are ineffective and cannot be made use of in many 
others. Under these circumstances other methods of attack must be 
resorted to, and in general, insecticides of various kinds, fitting the 
particular nature of the injury and of the insect causing it in each case, 
have proved successful. Insecticides are substances which may be 
placed upon a plant, or elsewhere, to be eaten by the insect and which 
when eaten, kill the insect; or materials which on coming in contact with 
the body of the insect, kill it as a result of that contact. Poisonous 
gases and vapors v/ould also be included as insecticides, as thus defined. 

CLASSES OF INSECTICIDES 

The materials used as insecticides fall into two general groups: (1) 
Those which are placed upon the food eaten by the insect, swallowed 
with it, and which upon entering the stomach are dissolved, producing 
inflammation and finally death. Such poisons can, of course, be used 
only for insects with chewing mouth parts which bite off and swallow 
solid food, such as pieces of leaves, stems, etc.; (2) Those which, when 
they come in contact with the body of an insect either enter the spir- 
acles and penetrate their chitinous lining and kill the tissues beyond; 
or which corrode the body; daprive it of oxygen; or by softening the 
coverings over ths body (scale insects) cause these to adhere to the 
plant it is on, killing the insect in any case. The materials of the first 
group are usually called stomach poisons; those of the second, contact 
insecticides. The latter could also be used for biting insects but the 
difficulties in the way of their being successfully applied are such that 
stomach poisons are used whenever possible. 

In reaching the insects concerned, either with stomach poisons or 
contact insecticides, the methods of conveying the material to where 
the insect is, and of an even and thorough distribution of it are important. 
Those substances which are solids in the form of fine powders can be 
blown onto the tree or whatever the insect may be on, but some are 
liquids. Accordingly, "powder guns" for spreading the poisonous 
dusts have been used with considerable success, and pumps with a fine 
nozzle at the end of a line of hose are used for the liquids. 

43 



44 APPLIED ENTOMOLOGY 

With stomach poisons, however, the poison is not necessarily eaten 
by the insect as soon as it falls on the plant, but must or should remain 
there for some time, as the insects may appear during a period of several 
days or even weeks. During this time much, probably most, of the 
poisonous dust would be blown off and the treatment be of little value. 
In spite of this difficulty, much successful work has been done with dry 
stomach poisons, and they have many advantages over sprays under 
certain conditions. 

It has been found that when stomach poisons are mixed with water 
and sprayed onto plants in the form of very fine droplets, the spray 
appearing like a fine mist, each droplet soon dries, leaving behind it 
the poison it contains, adhering to the leaf, where, unless washed off by 
rain, it will remain a long time. This has led to the general adoption of 
spraying, both with stomach poisons and contact insecticides, despite 
certain difficulties which have developed. 

STOMACH POISONS 

Arsenic is the basis of nearly all the commonly used stomach poisons, 
for though probably more than 50 materials have been tested, only a 
few have proved at all satisfactory, and with two or three exceptions, 
useful only under special conditions, they have all been arsenical com- 
pounds. It would seem natural under these circumstances to use 
common white arsenic (AS2O3) as the stomach poison, it being, when 
pure, 100 per cent arsenic (arsenious oxid). But it is found that arsenic 
dissolves to some extent in water, and that thus dissolved it destroys 
("burns") the places on the leaves on which it falls. This result is as 
bad for the plant as it would be to have the leaves eaten, for the object 
of spraying is to prevent injury or loss of leaf surface. Because of its 
solubility in water, therefore, arsenic, as such, is not employed as a spray, 
but combinations of it with other materials, not, or only very slightly 
soluble, have been selected for use instead. This produces another diffi- 
culty. A combination with lead can be obtained for example, which is 
almost absolutely insoluble in water and therefore entirely safe for use 
as a spray. But in this material only about one-quarter of it is arsenic, 
so that an insect, speaking in a general way, would be obliged to eat 
about four times as much before being poisoned, as would be the case had 
the material been arsenic instead. By the use of more or less insoluble 
combinations of arsenic with other substances, then, reduced injury to 
the foliage can largely be secured, but a larger leaf surface is consumed by 
the insect before the poisonous dose is obtained. This is a small matter, 
however, as compared with the protection of all the foliage on a tree from 
injury by the spray. 

Another difficulty in the use of sprays is the weight of the poison 
mixed in and carried by the water. It has just been pointed out that 



INSECTICIDES IN GENERAL: STOMACH POISONS 45 

the poison must not dissolve, or burning of the foHage will result. The 
poison, instead, must be suspended in the water, which acts merely as a 
carrier from the pump to the plant over which it distributes the poison. 
This distribution should be as uniform as possible in order that all parts of 
the plant may be equally well protected and covered. If the poison be 
heavy, settling quickly to the bottom of the pump, uneven distribution 
will result, some parts of the plant receiving too much of the poison while 
others will get but little. The best stomach poison from this standpoint 
therefore, is one which is so light that after mixing it with water it will 
take a long time to settle to the bottom. 

The chief stomach poisons now in use in the United States are Paris 
green. Arsenate of lead, Arsenate of lime. Hellebore, and Sodium fluorid, 
the last two having only a limited application. Standard formulas for 
these are given below. Variations from them will be found in connection 
with the special cases where change from the standard is desirable. 

Paris Green. — This was probably the first stomach poison used against 
insects, having been first employed about 1868 for the treatment of the 
Colorado potato beetle. Chemically, it is a combination of copper, 
arsenic and acetic acid, containing when pure, nearly 60 per cent of arsenic, 
which is high as compared with the other arsenicals in use, and this gives 
the substance its chief value. 

Paris green has three serious disadvantages. One of these is that 
some of the arsenic will dissolve in the water it is mixed with, causing 
injury to the foliage. This can in part be avoided by the addition of lime, 
which combines with any of the arsenic that separates from its combina- 
tion with the copper and acetic acid and would cause burning, converting 
it into arsenite of lime which is only slightly soluble under such circum- 
stances. Sometimes though, a slight burning takes place, even under 
these conditions. By Federal law, not over 3 per cent should be soluble. 

A second disadvantage is that Paris green is a heavy substance, 
settling quickly through the water to the bottom of the pump, which 
results in an uneven distribution over the plant. 

The third disadvantage is that it does not adhere well to foliage, being 
easily washed off by rains. This means that more frequent sprayings are 
necessary for the protection of the plants than would otherwise be the 
case, involving greater cost for material and labor. 

A standard formula for Paris green is: 

Per Bakrel Per Gallon 

Paris green >3 lb. ^2 teaspoonful (level) 

Quick lime 1 lb. 1 teaspoonful (level) 

Water 50 gal. 1 gal. 

Use fresh stone lime, slaking this in some of the water: work up the Paris 
green to a paste in a little of the water: add the lime slaked, to the rest of 
the water, then stir in the Paris green paste. It is not advisable to mix 



46 APPLIED ENTOMOLOGY 

this long before it is to be used, nor to mix more than will be used the 
same day. 

Although the addition of lime to the Paris green reduces the danger 
of injuring foliage, some plants even then, are liable to be burned some- 
what. Accordingly, the amount of the poison to use per barrel will vary. 
Thus, for potatoes the Paris green can usually be increased to 3^^ lb. per 
barrel, while for the peach it is not safe to use more than }/q lb. It 
should not be used on evergreens. 

Applied as a dust it is usually thoroughly mixed with flour, plaster or 
air-slaked lime, in about the proportion of 1 part of the Paris green to 
from 6 to 10 parts of the other, by weight. 

Paris green is unsafe to apply on stone fruit foliage, and because of the 
danger of burning in general, it is now less used than was once the case, 
arsenate of lead having largely replaced it as a spray. 

Arsenate of Lead. — The value of this material as a spray against insects 
was discovered about 1892 in the course of the work conducted by the 
State of Massachusetts on the control of the gypsy moth, and it has now 
been generally adopted as being, under ordinary conditions, the best 
stomach poison to use. Two forms of it are available : the basic or neu- 
tral (ortho) arsenate, Pb3(As04)o and the acid arsenate, PbHAs04. In 
pure condition the former is about 25 per cent arsenic oxid and the latter 
about 33 per cent. The latter is the form in most general use, but on the 
Pacific Coast, because of local conditions, the former appears to be re- 
garded with more favor. 

Arsenate of lead may be obtained both as a paste and as a powder. 
By law the paste must not be more than half water, but with about this 
amount present the percentage of arsenic oxid in it is reduced to from 
12 or 13 to 19 or 20 per cent. In the powder, water being practically 
absent, about 32 to 33 per cent is arsenic oxid. As the average in the 
paste is usually 16 per cent and the price of the powder is about double 
that of the paste, there is little choice between the two so far as the arsenic 
is concerned. The Federal law requires that in the paste no more than 
0.75 per cent of the arsenic oxid shall be soluble in water. 

Either form of arsenate of lead shows well on the foliage, which is 
useful, enabling the sprayer to see parts he has missed in spraying, and 
to "touch up" those places. It is also very light, settling slowly in the 
pump. Under most conditions arsenate of lead does not burn the leaves, 
being in fact, the safest of the stomach poisons in this regard, and it 
adheres to the leaves longer than the others (stomach poisons). On 
the other hand, it acts slowly on insects because of its rather low arsenic 
content 

As a pound of the paste is approximately one-half water, it is necessary 
in spraying a given area to use twice as much (by weight) as of the 
powder, in order to supply equal amounts of the poison. 



INSECTICIDES IN GENERAL: STOMACH POISONS 47 

A standard formula for arsenate of lead is: 

Per Barrel Per Gallon 

Arsenate of lead paste 3 lb. 3 teaspoonfuls (level) 

Water 50 gal. 1 gal. 

Arsenate of lead powder IH lb. 9}4 teaspoonfuls (level) 

Water 50 gal. 1 gal. 

In mixing the paste it is well to add some water and stir thoroughly 
before adding the rest of the water, in order to get a more uniform mix- 
ture. If it is allowed to dry it will not work up well thereafter by adding 
water, and it is also injured by freezing. 

Arsenate of Lime. — This substance has come into use since about 
1914, because of the rapidly increasing cost of arsenate of lead. It 
is Ca3(As04)2 and may be obtained, like arsenate of lead, either as a paste 
or a powder. The former contains about 18 per cent of arsenic oxid, 
and the latter about 44 per cent, thus being slightly higher in paste form, 
and considerably higher in powder form, than arsenate of lead. As the 
costs of the two forms differ correspondingly, there is little choice between 
them from this standpoint, but convenience and other factors give a slight 
preference to the powder. Being stronger than arsenate of lead, less 
needs to be used in order to supply an equal amount of poison to a given 
area. 

Arsenate of lime is not safe for use on foliage, and particularly that of 
stone fruits, unless an excess of lime is present. Accordingly, as was the 
case with Paris green, lime must be added to the mixture. 

A standard formula for arsenate of lime is: 

Per Barrel Per Gallon 

Arsenate of lime paste 2 lb. 13^ teaspoonfuls 

Quick lime 2 to 3 lb. 2 teaspoonfuls 

Water 50 gal. 1 gal. 

Arsenate of lime powder ^^ lb. 4^^ teaspoonfids 

Quick lime 1 lb. 9 teaspoonfuls 

Water 50 gal. 1 gal. 

The quick lime, which should be fresh stone lime, is slaked in some of 
the water, then added to the rest, and the arsenate of lime thoroughly 
stirred in. 

While this material is cheaper than arsenate of lead and perhaps 
kills a little more quickly, it has not been in use long enough to be certain 
just what results may be expected in all cases. At least it may at the 
present time be termed a very promising insecticide. 

Poison Baits. — These are included here, as, in most cases at least, 
they contain an arsenical poison. They are used mainly for the control 
of cutworms and grasshoppers. There are several formulas proposed. 



48 APPLIED ENTOMOLOGY 

but those consisting of bran or horse manure, poisoned with arsenic or 
Paris green, and made attractive to the insect by adding strong-smelHhg 
molasses (syrup) and the juice of citrus fruits, have in general been the 
most successful. Detailed consideration of them will be given in con- 
nection with the insects for which they are used. 

Hellebore. — This is the powdered roots of the plants Veratrum 
album and Veratrum viridis. It is a mild stomach poison and can 
therefore be used with safety to man, on plants soon to be gathered for 
food, as it loses its strength quite quickly on exposure to the air. It is 
sometimes difficult to obtain fresh. 

It may be dusted over the plants, sticking on best if applied while dew 
is on them, or it may be mixed with from one to three times its hvXk of 
flour or plaster, for this purpose. It may also be used as a spray by 
steeping an ounce in a quart of water and then adding another quart of 
water. At the rate of half a pound in 10 gal. of water it is effective against 
house-fly maggots in manure piles. It is too expensive to use except on a 
small scale. 

Commercial Sodium Fluorid. — This substance has recently been found 
to be effective for some insects, acting apparently both as a stomach 
poison and as a contact insecticide. It is applied as a dust, either 
pure or mixed in about equal parts, with flour or plaster. Details are 
given in connection with the insects against which it is used. 



CHAPTER VTII 
CONTACT INSECTICIDES 

For insects which cb not feed upon soHd food, stomach poisons are 
useless, and sprays which come in contact with, and kill them in one or 
another of the ways already indicated, must be used. This is unfortunate 
for it means the most thorough kind of work if all the insects are to be 
reached by the spray. It is among such insects too, that the greatest 
difficulties in accomplishing this, occur. Some, though large enough to be 
almost certainly reached by the spray have a particularly thick outer 
shell: others are exceedingly small and thus can find protection under 
buds, in crevices of the bark and in other places where the spray may not 
reach them: still others form protective coverings (scales) over them- 
selves, which fit tightly to the objects they may be on, so that a successful 
spray must be very strong and penetrating: and finally, many of the 
smallest and also of the scale-protected insects have marvelous powers of 
increase, so that if even a single individual escapes treatment, a few 
days or a week or two will find the plant again swarming with these 
insects. 

Every insect therefore, which can be killed by a stomach poison is 
best controlled by such materials. For the others, oils, soaps, nicotine, 
sulfur compounds and a few other substances of minor importance serve 
as contact insecticides. 

Considering the oils first, there are several which are of use. Among 
mineral oils, crude petroleam and kerosene are destructive to insect life 
but so dangerous to plants when of full strength, that some method of 
dilution becomes necessary. 

Kerosene Emulsion : standard formula : 

Common laundry soap 3*^ lb. 

Soft water 1 gal. 

Kerosene 2 gal. 

Dissolve the soap in the water (best by shaving it into hot water) : 
then add the kerosene and with a small hand spray pump having a fine 
nozzle, draw the mixture into the pump and out through the nozzle back 
into the dish from which it was drawn. In a few minutes it should 
become creamy and then begin to thicken. When it has become so 
thick as to go hard through the pump, this process has been completed, 
4 49 



50 APPLIED ENTOMOLOGY 

giving a Stock Solution in which the oil, broken up into very tiny droplets, 
will not run together again and the water can dilute the mixture. For use 
against soft-bodied insects, 1 part of the Stock Solution is mixed with 
about 9 parts of water to spray, while for tougher insects, 1 part is diluted 
with 4 or 5 parts of water, though this strength may sometimes injure 
the plants somewhat. The Stock Solution, if well prepared, should keep 
before breaking down (shown by a film of oil appearing on the surface) 
for at least a month or two. If the materials fail to thicken in the pump 
it is probably because the water is "hard water." In that case add a 
little borax or soda to soften it. 

Crude Petroleum can be used in place of kerosene in preparing this 
emulsion, provided the right grade can be obtained, but this is often 
difficult, and so is not frequently done. 

Miscible Oils. — These are stronger than kerosene emulsion. They 
contain mineral oils, a small amount of vegetable oil, naphthaline in 
some cases, some alkali, and water. Properly made they dilute readily 
with water. 

A number of brands of miscible oils are on the market, prepared 
mainly as sprays for the control of scale insects. For winter use against 
scales they are generally diluted at the rate of 1 part of the oil to 12 
to 14 parts of water. When used in summer against plant lice the dilu- 
tion should be about 1 part to 35 to 40 parts of water. 

The material should not be used if free oil stands on it, as this shows 
that it has broken down and is not safe on the plants. If sprayed on trees 
in freezing weather it may gather and freeze in cracks of the trees, in- 
juring them. It is easy to handle and spreads readily from where it 
strikes, covering more than wovild otherwise be the case, but it has been 
claimed, with considerable evidence to support it, that repeated treat- 
ments with miscible oils cause a cumulative injurious effect on trees. 

Among soaps, common laundry soap and whale-oil (generally fish-oil 
now) soap are the usual materials used as insecticides. 

Whale-oil Soap. — This is a soap made by combining fish oil with an 
alkali, preferably potash. It is usually diluted at the rate of 1 lb. to 5 
or 6 gal. of water to apply against plant lice and similar soft-bodied 
insects in summer, but is also a fair winter application for scale insects, 
at the rate of 2 lb. per gallon of water, though more costly than other, 
equally good materials. 

Common Soap. — This is a fairly good material at the rate of 1 lb. in 
3 to 5 gal. of water for summer use against plant lice and other soft- 
bodied insects but is not as effective as whale-oil soap and is mentioned 
only because the latter cannot always be obtained. 

Nicotine. — This is an alkaloid which occurs in tobacco. It can be 
obtained by soaking tobacco stems in warm water till a dark brown liquid 
containing nicotine is obtained, and this is of some value as an insecticide. 



CONTACT INSECTICIDES 51 

Tobacco dust is also used around plants as an insect repellent as well as a 
fertilizer. 

Nicotine obtained as above indicated, is variable in its strength and 
the amount it should be diluted for use is uncertain. It is also quite 
volatile and this is a disadvantage when it is used as a spray. Com- 
mercial nicotine compounds on the market avoid these difficulties by 
supplying a material containing a fixed percentage of nicotine combined 
with sulfuric acid, known as nicotine sulfate 40 per cent. This can be 
diluted to the proper strength with accuracy, and does not pass off into 
the air rapidly. Nicotine uncombined, of the same strength, can also 
be obtained, but should be used for fumigation and not as a spray. 

Nicotine sulfate is an excellent material to use for plant lice and other 
delicate insects. It is generally diluted at the rate of 1 gal. to 800 or 
1,000 gal. of water, and in some cases a greater dilution even, than this is 
possil:)le. Sometimes dilution at the rate of 1 to 500 is desirable. 

Standard formula for nicotine sulfate 40 per cent, 1 part to 800 of 
wat(M-: 

Per Barrel Per Gallon 

Nicotine sulfate, 40 per cent )-2 pint 1,^^ teaspoonfuls 

Soap 2 to 3 lb. 1 oz. 

Water 50 gal. 1 gal. 

Three-eighths of a pint in 50 gal. of water, or 1 teaspoonful in a 
gallon, gives nearly a dilution of 1 to 1,000. The addition of soap 
causes the material to spread more and adhere better. 

Among the various sulfur compounds, those with lime have thus far 
been foimd to be the most successful. 

Lime-sulfur Wash. — ^This is prepared by boiling lime and sulfur 
together in water. Several substances are produced by this boiling, 
but apparently its insecticidal value is determined by the quantity of 
calcium polysulfids (CaS^ and CaSs) and possibly the calcium thiosulfate 
(CaS203) which are formed in the mixture. The wash can be made at 
home but it is generally easier to buy it in concentrated form and dilute 
as needed. It will vary in specific gravity in different cases, and its 
reading must be taken (a Beaume hydrometer is generally used for this 
purpose) in order to dilute it properly. The range in readings of differ- 
ent lots may vary as much as 5° or more, but is usually about 33°Be. 
Thus, a sample of this density should have 63^-^ gal. mixed with 43^ gal. 
of water to be of the proper strength for use as a winter spray for the 
San Jose Scale, when this insect is dormant; while if its density is 30°Be., 
7 gal. should be mixed with 43 gal. of water. Tables of density, Beaum^ 
readings, and the amount of concentrate to add to water to make a total 
of 50 gal. of spray, both for winter use and as a foliage spray in summer, 
can be obtained by applying to any state experiment station or to the 
U. S. Bureau of Entomology. 



52 APPLIED ENTOMOLOGY 

The Lime-sulfur wash is used both as a strong spray against insects 
during their dormant season, and as a weaker one for general purposes 
during the summer. In the latter case, besides being a contact insecti- 
cide, it has a little value as a stomach poison. It cannot safely be used 
on stone fruits or potatoes, however. 

This material must be kept in air-tight containers as it decomposes 
on standing when exposed to the air. A film of some vegetable oil over it, 
for partly filled containers, will give this protection. It should not be 
allowed to freeze. 

For stone fruits where a summer treatment seems necessary, self- 
boiled lime-sulfur may be used. This is prepared by slaking 8 lb. of 
fresh stone lime in a barrel, in enough water to nearly cover it. Eight 
pounds of fine sulfur should be gradually added to this, as soon as the 
lime begins to slake, running the sulfur in through a sieve to break up any 
lumps. This mixture should be constantly stirred and more water 
added to form first a thick paste, then gradually a thin one. The heat 
produced by the lime in slaking will cause the mixture to boil for several 
minutes. When slaking is at an end, cool the mixture rapidly by adding 
considerable water, then strain into the pump to remove lumps of lime, 
but working any lumps of sulfur through the strainer; then dilute with 
water to a total of 50 gal. 

Dry Sulfur Compounds. — These substances have recently appeared 
in competition with the lime-sulfur wash, the advantages claimed for 
them being ease of handhng, reduction of shipping charges, no deteriora- 
tion on standing, and equal efficiency at lower cost. 

These substances are sulfid combinations with either potassium, 
sodium, barium or calcium. The amount of sulfur present varies greatly 
in different brands. They do not contain as much of the polysulfids 
which appear to be the actual insecticides of the lime-sulfur wash as the 
liquid wash, and even the amount of sulfur present in them, after the 
addition of water according to directions, is less than in an equal quantity 
of the wash, so that basing efficiency oh the amount of sulfur, regardless 
of its form, the amounts of these dry materials would have to be greatly 
increased to equal that of the wash, and would therefore seriously increase 
their cost. At the present time their value cannot be considered as 
having been finally settled though in many cases field tests of them have 
given good results. Continued studies and tests of these materials are 
needed to determine their real value. 

Sulfur. — This substance in the form of a very fine powder, can be 
dusted over plants for the destruction of red spiders and other mites, 
or it may be made into a paste with soapy water, using 10 lb. of sulfur 
and 2 lb. of soap in 50 gal. of water, and applied as a spray Its use is 
rather limited and its actual value somewhat questionable in many cases. 



CONTACT INSECTICIDES 53 

Pyrethrum, Insect Powder or Buhach. — This is made by grinding 
up the blossoms of certain plants, which contain an essential (and volatile) 
oil effective against insects but not injurious to man. Its use is mainly 
limited to small areas, and best, those which can be tightly closed. 

Various other materials will be considered in connection with the 
particular insects, for the control of which they are used. 



CHAPTER IX 
INSECTICIDES AND FUNGICIDES: FUMIGATION 

COMBINATIONS OF SPRAY MATERIALS 

The greater part of the cost of spraying comes from the time and 
wages of the workers, the materials used being rather inexpensive in 
comparison. Wherever it is possible therefore, to make two or three 
applications at once by using combined sprays, the cost is much reduced. 

Frequently there are cases where the application of a stomach poison 
for chewing insects and of a contact insecticide for sucking forms, can 
be made at about the same time. Treatment for fungous diseases may 
also be desirable, and a satisfactory mixed spray for all three purposes 
can often be given. Certain precautions must be taken in mixing sprays, 
however, as in some instances the materials of two or more sprays, when 
combined, will undergo changes, producing substances injurious to the 
plant or affecting the value of the spray for the purpose for which it was 
intended. 

No spray material containing soap should be combined with one con- 
taining lime, as when these materials are brought together, a calcareous 
and insoluble soap is formed. Thus, when nicotine sulfate is used with 
lime-sulfur or Bordeaux mixture, the soap usually added to the former 
must never be put in. Arsenate of lead and compounds containing 
sodium or potassium sulfid, when mixed, produce sodium or potassium 
arsenate which is very soluble and will injure foliage, so this combination 
should also be avoided. 

Bordeaux mixture, a fungicide, combines well with most of the insec- 
ticides except those containing soap, but as it contains lime, an insec- 
ticide with soap is not safe for this combination. In most cases the 
Bordeaux mixture ready for spraying can be regarded as an equivalent 
amount of water, to which to add the insecticide. For example, in 
combining Bordeaux and arsenate of lead, simply add 3 lb. of the paste 
to 50 gal. of the Bordeaux. 

Bordeaux mixture will safely combine with any of the arsenical 
poisons given in this book, and also with nicotine sulfate if the soap 
be omitted. Lime-sulfur at summer strength may be used with arsenate 
of lead or nicotine sulfate, leaving out the soap, though in the former 
case a decomposition is liable to take place which reduces the value 
of the material. Lime-sulfur at winter strength when added to the 

54 



INSECTICIDES AND FUNGICIDES: FUMIGATION 55 

arsenate of lead brings about a decomposition, as a result of which con- 
siderable soluble arsenic is formed, and the efficiency of the lime-sulfur 
is also reduced about one-third. This may be avoided, however, by 
slaking 5 lb. of quick lime and adding this to the lime-sulfur before putting 
in the arsenate of lead. 

Lead arsenate can be combined with nicotine sulfate, and in some cases 
at least, with kerosene emulsion. With soap, acid lead arsenate decom- 
poses to some extent forming a soluble arsenate which is dangerous on 
foliage. Small amounts of soap added as a "sticker," however, are often 
advantageous even in spite of this decomposition and are frequently 
recommended, the gain by the addition of the soap being greater than 
a small injury by burning. 

FUMIGATION 

In theory, fumigation is the best method for the control of insects. 
A gas will reach every portion of a room or a plant, penetrating where no 
spray can reach, so that insects no matter how well concealed in crevices, 
under bark or in other locations, will be reached. Still, practical diffi- 
culties in the use of poisonous gases are numerous and result in a restricted 
use of this method of treatment. 

The gases used for the destruction of insects act either as actual 
]:)oisons which enter the body through the tracheal system and directly 
attack the tissues, or combine with the oxygen of the air and thus remove 
it from availability by the insect, which suffocates in consequence. In 
either case, successful fumigation depends upon the liberation of a suf- 
ficient quantity of the gas or vapor to make it strong enough to kill the 
insect. 

This at once eliminates trees, bushes and crops growing out of doors 
from consideration, unless they or their products are so valuable as to 
make the use of gas-tight tents to cover them during treatment worth 
the expense, which is considerable. Accordingly, fumigation is generally 
made use of only with citrus trees, and in houses, greenhouses or other 
places capable of being tightly closed. Under the conditions mentioned, 
however, it is an excellent method for insect control, though where plants 
are to be fumigated, it is usually done at night as the gases or vapors are 
less liable to cause injury then. 

The fumigants most often used are carbon disulfid, nicotine, sulfur 
and hydrocyanic acid gas. 

Carbon Disulfid (CS2). — This is obtained in liquid form but becomes 
a gas on exposure to the air. Impure grades are as good for fumigation 
as the purified article. The number of cubic feet in the space to be fumi- 
gated is calculated, and in general from 10 to 20 11). of the disulfid 
are used for each 1,000 cu. ft., though if the place is very tight, less than 
this will be needed. As the gas is considerably heavier than air, the usual 



56 APPLIED ENTOMOLOGY 

practice is to put the liquid in rather flat dishes close to the top of the 
place to be fumigated, as the gas will develop more rapidly in such dishes 
and work downward from its source. All openings into this place must 
then be tightly closed at once and everything be left undisturbed for from 
24 to 48 hr. Ventilate well from outside before entering. 

The chief disadvantage in the use of this gas is that it is quite inflam- 
mable and cannot be used near where there is a fire or highly heated pipes 
of any kind. In such quantities as the operator is likely to inhale while 
using it, a headache is generally the most serious result, though persons 
with heart trouble of any kind should not work with it as it has some effect 
on that organ. 

Carbon disulfid is used chiefly against clothes moths, carpet beetles, 
stored grain pests, pea, bean, and other seed pests, ants, and borers in 
trees. It cannot safely be used in greenhouses or with plants. Details 
of its uses in different cases will be given in connection with the different 
insects concerned. 

Nicotine. — Nicotine as a vapor may be obtained by evaporating the 
decoction of it mentioned in the last chapter, in a dish over a lamp, but 
the uncertainty as to its strength makes treatment in this way liable to 
prove unsatisfactory. 

Nicotine 40 per cent, both in liquid form and as paper rolls saturated 
with it, are on the market and supply a material of known strength with 
which to work. It is of value as a treatment for plant hce and other 
delicate insects. A fluid ounce added to a little water, and this evapo- 
rated by heat will be sufficient for about 1,000 cu. ft. of space, provided the 
place is quite tight; or four or five sheets of the paper are usually enough. 
Upon lighting, the paper smolders, giving off the nicotine vapor. The 
length of time necessary for nicotine treatment varies with different 
insects, but is generally begun in the evening, continued all night, and 
the place opened and aired the next morning. 

Sulfur. — The value of sulfur as a fumigant is probably due both to its 
combination on burning with the oxygen of the air, eliminating this and 
suffocating the insect, and to the formation in this way of a poisonous gas. 
It is prepared by burning powdered sulfur in the place to be fumigated, 
and is used for household pests and also in greenhouses between crops. 
It cannot be safely used with Hving plants. From 1 to 2 lb. of sulfur per 
1,000 cu. ft. of space is the usual quantity used. Polished metal surfaces 
in the place to be fumigated will become tarnished by the gas, and these 
should be removed, as well as colored goods which are bleached by it. 
Metal can be protected by covering it with vasehne. 

The general practice is to place a large iron kettle on bricks to keep 
it off the floor, which in that place should be covered for a distance of 
several feet with something which will not be injured or burned if the 
sulfur spatters over. In the kettle place the sulfur and add to it a little 



INSECTICIDES AND FUNGICIDES: FUMIGATION 57 

denatured alcohol to insure burning : then light the sulfur and keep the 
place tightly closed for 24 to 48 hr. ; then air thoroughly. 

Hydrocyanic -acid Gas (HCN), — This is one of the most powerful and 
dangerous gases known, and persons having had no training in its use are 
advised not to try it. It is produced by the addition of sodium or potas- 
sium cyanid to sulfuric acid which has been diluted with water. Formerly, 
potassium cyanid was used almost entirely but now the sodium cyanid has 
taken its place. Care should be taken that the cyanid is of good quality 
and (at least for use with plants) contains no chlorine. If potassium 
cyanid is used it should contain 38 per cent of cyanogen : if sodium cyanid, 
51 to 52 per cent. The sulfuric acid should have a specific gravity of 1.83 
and be free of any nitric acid. 

Hydrocyanic-acid gas can be used to advantage in the following ways: 

(a) For household and storehouse pests and for fumigating bales of 
imported cotton. 

(6) For greenhouse insects. 

(r) For insects on dormant nursery stock. 

(d) For insects on citrus trees. 

For the first class, an ounce of sodium cyanid for every 100 cu. ft. of 
space is used, and at least 2 hr. of fumigation is necessary. 

For greenhouse insects the dose is }2 to ^ oz. of sodium cyanid for 
every 1,000 cu. ft., with a fumigation period of ^ to 1 hr. This treatment, 
at a temperature of about 65°F. and a low percentage of atmospheric 
moisture, should be given only after dark. Some of the more delicate 
varieties of plants may be somewhat injured by this, but in all probability 
much less than by the continued attacks of the insects. The plants 
should be dry (not watered recently) at the time of treatment. 

Dormant nursery stock should be treated with ^ to 1 oz. of sodium 
cyanid for every 100 cu. ft., for 1 hr. The stock should not be wet nor 
very closely packed. 

For the fumigation of citrus trees during their dormant or most 
nearly dormant season (October to January) % to 134 oz. of sodium cya- 
nid should be used for every 100 cu. ft. of space for a period of ^ to 1 hr. 
The value of good citrus trees is such that gas-tight tents are made and 
used for fumigating them. 

In using potassium cyanid, one-fourth more should be taken as the 
dose than indicated above. 

Before treating any place to be fumigated, determine the number of 
cubic feet in the place and weigh out the proper amount of cyanid. Tak- 
ing this quantity as the unit from which to determine the amounts of 
sulfuric acid and water for this dose, measure out 13^^ times as much of 
the acid in fluid ounces and twice as much water, also in fluid ounces. 
Thus if the space to be fumigated calls for 43^2 oz, (by weight) of the 
cyanid, 6% fl. oz. of the acid, and 9 fl. oz. of water will constitute the 



58 APPLIED ENTOMOLOGY 

dose. With potassium cyanid the proportions of the materials differ 
somewhat from this, being 1 part of the cyanid, 1 part of the acid and 
3 parts of water. 

Granite-ware dishes, without flaws exposing the metal, are excellent 
containers for this work. They should be considerably larger than are 
needed to hold the dose, and for large areas it is often desirable to divide 
this among several containers. First, place the proper amount of water 
in the container; then add the acid slowly to avoid spattering and the 
production of too much heat; lastly, drop in the cyanid, which it is desir- 
able to have loosely wrapped up in tissue paper in order to gain a mo- 
ment's time in getting out before the gas begins to l)e given off freely. 

Great care must be taken to leave the place instantly after adding 
the cyanid to the acid and water, and at the end of the fumigation period 
there should be a thorough airing for at least a quarter of an hour l^efore 
entering. If there are windows, these should be opened from the outside 
only, and under no circumstances should the operator enter too soon. 



CHAPTER X 
THE RELATIONSHIPS OF INSECTS 

Classification may be defined as the orderly arrangement of different 
objects into groups. Any articles can be classified in one way or another: 
chairs for example, can be brought into groups according to the kinds of 
wood of which they are made; or whether they are upholstered or not; 
or according to their price, and any of these might be equally useful. 
With living things, however, the problem becomes one of a "natural" 
as opposed to an "artificial" classification. 

It is now the general belief that the first animals were extremely 
simple in structure, and that in the course of generations (and centuries) 
variation in their descendants led to the production of different forms, 
and finally to all the multitudes of kinds now in existence. This devel- 
opment has often been pictured as a tree, the trunk representing the 
original animals, which, varying as individuals of the same kind always 
do, began after a time to show several distinct lines along which the 
variation took place. This would be represented in the tree by the lowest 
branching of the trunk. Each main limb under the influence of the same 
conditions would fork in its turn, perhaps into two, perhaps more, and 
this process repeated again and again would finally produce the ter- 
minal twigs — the present animals. Thus each twig would represent all 
the indivi(hials of the same kind; i.e., a single species; those nearest it 
the other species most closely related to it; and those on another part 
of the tree, though species and also related, would only be distantly so, 
and of course, quite different. 

A natural classification of animals therefore, is an attempt to express 
the actual relationships of the animals, placing nearest each other those 
most closely related. To do this, the total of their differences and re- 
semblances must be taken into account. Classification based on a single 
character then, is almost always unreliable. The division of insects into 
three main groups based on their metamorphosis, is an example of this, 
for .while it is entirely correct as a statement of facts, a classification 
using this character would bring near together many insects which in 
reality are only distantly related. 

The largest limb of the animal tree represents the original insects, 
not because they were so numerous at first, but because they now form 
such a large part of animal life. This limb is usually called a Class, 
while the still more comprehensive groups considered in Chapter I are 
called Phyla. These are the main divisions of the tree. In this case 
the Hexapoda is the name given to the insect class. 

From all the evidence available, the original insects were at least 

59 



60 



APPLIED ENTOMOLOGY 



comparatively small, wingless, and with practically no metamorphosis. 
After a time many of their descendants began to develop wings, and a 
fork of the Class was produced, one branch (or Subclass), the Apterygota, 
apparently retaining much of its former character, while the other sub- 
class became the Pterygota or winged insects. These have increased 
greatly in abundance, and their variations have resulted in the produc- 
tion of many branches passing outward toward the twigs, named in 
sequence. Orders, Families, Genera and Species. Intermediate branch- 
ings between these often also need recognition and are called Suborders, 

Mecop-f-era-. 
Nyrmnopfera.^ 

Homopfera- 
Mzmipfera---A 



Anoplura- 

Ma!lophaga-> 
Corrodsnh'a-' 



Hexapoda 




DipierL.. 
Siphonapizra 



Lepidop-fera 
Irichopf&ra 



Neuropfera 

^Sfrepsipfera 
Coleophra 

^ Dermaphra 

Embiidina 

Pkcophra 

'Odonah 
Ephemerida 



PhrLjgoi-a 



t~Thusanura 

Collembo/a 
Aphrijgo-ta 



Fig. 34. — Diagram suggesting possible relations of the orders of insects to each other, 
expressed in a tree-like way: the Hexapod limb. 



Superfamilies, etc., as may be necessary. The twigs each represent a 
single species, but here we may recognize subspecies, varieties, races, etc., 
among which the individuals which together constitute the species, are 
distributed. 

In any consideration of the different groups of insects one must 
necessarily follow after another through the book, and when four groups 
for example, are equally near relatives, the first and fourth treated may 
thereby appear more distant than is really the case. 

Between the fork of the insect limb which produced the Apterygota 
and the Pterygota, and the twigs representing the species, the actual 



THE RELATIONSHIPS OF INSECTS 



61 



divisions of the branches are more or less uncertain. The sp'ecies in 
general, group themselves quite easily into different genera and these 
into families; but while these last can in most cases be definitely placed 
in their orders, their correct relation to each other is often debatable. 
The relation of the orders to each other is far from settled, and while 
some are evidently more closely allied than others, within certain limits 
one order could follow another in almost any sequence without any serious 
loss to the expression of relationships. Where orders appear to be closely 
allied to each other, this will be indicated in connection with their 
consideration. 

With the relations between the orders and also the families within 
the orders, still uncertain in many cases, a tree showing these must of 
necessity express only the views of the individual who drew it. Such a 
tree carried to the species would be entirely too large for these pages 
(there are about 80 families of beetles, and many of the other orders have 
large numbers also), but one carried to the orders is given here (Fig. 34) 
to illustrate the general idea of a tree-like classification. 

Expressed in tabular form, the classification followed in this book 
is given below. 

Class Sdbclass Order Suborder Common Name, or Examples 

ApterygotaJ Thj'sanura Silver fish, etc. 

Collembola Snow fleas, etc. 

Ephemerida May-flies 

Odonata Dragon-flies 

Plecoptera Stone flies 

Embiidina (No common name nor 

examples) 

Orthoptera Roaches, grasshoppers, 

crickets, etc. 

Isoptera Termites or White ants 

Dermaptera Earwigs 

Rhynchophora. . .Snout beetles 
Coleoptera vera . . True beetles 

Strepsiptera Stylopids 

Thysanoptera Thrips 

Pterygota { Corrodentia Book Hce; Psocids 

Mallophaga Bird lice (biting) 

Anoplura Sucking lice 

Hemiptera True Bugs 

Homoptera Scales, plant lice, leaf hop- 
pers, etc. 

Neuroptera Corydalis, aphis lions, ant 

lions, etc. 

Trichoptera Caddis flies 

Heterocera Moths 

Rhopalocera. . . .Butterflies 

Mecoptera Scorpion flies 

Diptera Flies 

Siphonaptera Fleas 

Hymenoptera Saw flies, ichneumon flies, 

ants, wasps, bees, etc. 



Hexapoda 



Coleoptera 



Lepidoptera 



CHAPTER XI 
THE APTERYGOTA 

These are all relatively small insects, some being nearly microscopic 
in size, while the largest are seldom more than an inch in length. They 
are all land animals though a few live near the ocean and are occasion- 
ally found in tide pools. They are widely distributed over the earth, 
some living in arctic conditions while others occur in the tropics, but 
nearly all at least, require a somewhat humid atmosphere. 

In this group the mouth parts seem to l)e typically of the chewing 
type. In many cases they are as much exposed as in most insects, but 
in some they appear to have been drawn into the head so that when not 
in use they are almost entirely concealed. Under such conditions they 
are often so slender as to be no longer of value for chewing, and are 
possibly used for rasping and sucking food. 

Some Apterygota have traces of abdominal legs (''vestigial legs"). 
Spine-like appendages, attached to the hinder margins of some of the 
abdominal segments beneath and called styli, may also occur. A 
ventral tube present in some Apterygota on the underside of the first 
abdominal segment may be simply a small projection partially divided 
into two, or it may be highly developed into two slender but delicate 
tubes which can be extended to a considerable distance. Its use is not 
known. 

Bringing together these facts, the Apterygota may be characterized 
as: 

Wirujless insects having the mouth parts either exposed and of the chewing 
type, or drawn into a cavity within the head where they are sometimes so 
slender as to be of no value for chewing but could possibly be used for sucking. 
In those with exposed mouth parts, more then one pair of styli is present on 
the back margins of the hinder abdominal segments: in those with mouth 
parts drawn into the head, styli, a ventral tube or traces of abdominal legs 
are present. 

Very few of the Apterygota are of any importance from an economic 
standpoint, but they are of much interest, being the simplest insects 
known and throwing some light upon the subject of the ancestry of the 
insect group. 

Two subdivisions, the orders Thysanura and Collembola, are generally 
recognized in the Apterygota. The Thysanura have styli present, 
while in the Collembola they are absent. Cerci, which are segmented, 

62 



THE APTERYGOTA 



63 



antenna-like projections backward from the end of the abdomen, occur 
in the Thysanura. Here they are two in number, rather long and con- 
sisting of many segments, except in a few cases where they have been 
transformed into a pair of good sized, unsegmented forceps. In the 
Collembola, cerci are either entirely absent or very small and consist 
of only one segment. 

THE THYSANURA 

The Thysanura average much larger than the Collembola. They are 
characterized as: 

Apterygota with styli on the underside of the abdomen, and with usually 
long, many-segmented cerci at the end of the body, except in a few species 
where these have become a pair of forceps. 

Only one Thysanuran is of particular eco- 
nomic importance in the United States; the 
Silver Fish or ''Slicker" (Fig. 35). 

The Silver Fish (Lepisma saccharina L.). — 
This little household pest is found both in 
Europe and this country. It is silvery gray in 
color, usually less than half an inch long, and 
very active and hard to catch. Besides the two 
long cerci at the hinder end of the body it has a 
similar "caudal filament" giving the insect the 
appearance of having three "tails." It pi-efers 
dark places and feeds on book bindings, 
starched clothing, or anything containing starch, 
and often loosens wall paper by feeding on the 
starch used to paste it to the wall. 

It may be controlled by placing on pieces of 
card, starch paste made as follows: Flour 1 

pint; Arsenic 3^^ to ^ oz.; water enough to make a thin paste after 
boiling. Spread this on the cards and place near where the insects arc 
found, for them to feed upon. Do not place the cards where young 
children can get at them. The Silver Fish prefers moist to dry places, 
so clothing should not be stored where it is damp. Sometimes Insect 
Powder dusted in the haunts of this pest is helpful. 

THE COLLEMBOLA 

The Collembola are usually very small insects, and being dark colored, 
in most cases are not often noticed. Most of this group have a "spring" 
attached near the hinder end of the body beneath. This consists of a 
single piece to which a pair of others are joined and the whole is carried 
pointing forward when not in use (Fig. 36). When the spring is suddenly 
pressed against the ground, the entire body of the insect is thrown into the 
air and a peculiar hopping or leaping motion results. 




Fig. 35. — S i 1 ve r F i a h 
(Lepisma t^accharina L.) 
about twice natural size. 
{After I4lh Rept. Minn. 
State Entomologist.) 



64 



APPLIED ENTOMOLOGY 



The Collembola may be characterized as: 

Apterygota without styli on the underside of the abdomen: cerci either 
absent or very small and. consisting of only one segment. Usually much 
smaller than Thysanura and most of them with a ventral "spring.'' 




Fig. 36. — Springtail {Papirius fuscus Lucas) showing forked "spring" projecting forward 
toward the head beneath the body. Greatly enlarged. From Lubbock.) 

The most famiUar members of this order are probably the Snow 
Fleas, which are sometimes seen in enormous numbers on snow, where 
their dark color and their hopping movements make them noticeable 
(Fig. 37). Some of the group often become a nuisance by gathering 




Fig. 37. — Snow Flea {Achorutcs nivicola Fitch) greatly enlarged. Real length M2 inch 

(From Folsom.) 

in maple-sap buckets on trees being tapped. Some also, feed on the leaves 
of plants making tiny holes, which though of themselves unimportant be- 
ing small, still afford the spores of fungous diseases excellent opportunities 
for entrance to the plant tissues. In cases where work of this nature by 
Collembola is sufficient to warrant it, spraying the leaves as soon as the 
injury appears, with arsenate of lead, standard formula, is effective. 



CHAPTER XII 
THE PTERYGOTA. THE EPHEMERIDA 

The group Pterygota includes practically all our common insects 
and is the main branch of the class Hexapoda, the Apterygota though 
of equal rank, being a mere twig in size, in comparison. 

As a whole the Pterygota are characterized by the presence of wings, 
though as already indicated, many of them for one reason or another 
have lost these structures. 

Almost all characters present in insects may be found in this section 
without referring to the Apterygota: practically all the pests and all the 
beneficial forms belong here; and their differences are so great that 22 
orders have been established as subdivisions for them. 

The 'earliest writers on insects did not regard these differences as of 
great importance, and called the groups families or gave them even lower 
rank. More recent workers, however, have regarded them as of greater 
significance, some students of the subject being inclined to recognize more, 
rather than fewer orders, and it is not at all unlikely that time will finally 
bring a general acceptance of 26 or 28 such groups instead of the first seven 
established by Linne, or the 22 here treated. 

THE EPHEMERIDA 

The Ephemerida, May-flies or shad-flies as they are often called 
(Fig. 38), are insects of medium or small size. The adults have delicate 
bodies and gauzy, fragile wings, the latter usually with many cross- veins. 
The fore wings are much larger than the hind ones, which in some cases 
are absent, and the former are in general, rather strongly triangular in 
outline. When at rest they are held vertically above the body. At 
the end of the abdomen two or three long threads, each composed of 
many segments and often called caudal filaments, are usually present, 
the. lateral ones being cerci corresponding to those in the Thysanura. 

The mouth parts of the adult May-fiy are of the chewing type, but 
so poorly developed that it is doubtful if they are ever made use of. 
In some cases they are even rudimentary. The reproductive organs 
differ from those in all the other groups, the ducts being not united on the 
middle line below, but opening separately to the outside — apparently 
the retention of a very primitive condition. The early stages are passed 
in the water, the nymphs breathing — at least after the first few molts — 
by tracheal gills. These are delicate, usually wing-like in form, and are 
5 ' 65 



66 



APPLIED ENTOMOLOGY 



outgrowths of the body wall. Into them pass tracheal trunks which 
branch again and again so that only their own walls and those of the gill 
itself separate the air in the tracheae from that in the water outside, and 
so thin are these layers that the oxygen in the water can pass through 
them into the tracheae, and carbonic acid gas pass olit. 

These insects add to their list of peculiarities also, the fact that after 
becoming full grown and being able to fly, they molt once more, even a 
thin layer over the final wings being shed. 




Fig. 38. 



-Adult May-fly {Hcxagenia variabilis Eaton) showiu 
size. {From Folso77i.) 



the Ions: 



Natural 



From these statements the group may be characterized thus: 
Inserts having as adults delicate bodies and usually four wings, the 
front pair much larger than the others (which are sometimes absent), and 
generally with many cross-veins: end of the abdomen with two or three long, 
caudal filaments composed of many segments: reproductive organs with two 
openings to the exterior: mouth parts of the chewing type but pradically 
rudimentary: nymphs living in water and with an incomplete metamor- 
phosis, the final molt coming after the wings have become fully developed. 
May-fiies are most abundant near streams and lakes, as their nymphs 
live in the water. The fully mature nymphs leave the water, usually 
in greatest numbers about sunset, and suddenly molting, extend their 
wings and fly off, but as above stated usually molt again within a few 
hours. As their flight generally begins about dusk and as they are 
strongly attracted to lights, they are often seen in multitudes around 
street lights during the evenings. 



THE PTERYGOTA. THE EPHEMERIDA 67 

The adults live only a few hours — not more than a day or two at 
most — but during this time the eggs are dropped into the water. The 
nymphs which hatch from them feed, probably mainly on vegetable 
matter at the bottom, though some are doubtless partly carnivorous. 
They live for one, two or three years, according to the species concerned 
(some have two generations each year), feeding, and molting with unusual 
frequency for insects (Lubbock observed 21 molts in one species), until 
they are full-grown. During this time the mouth parts are well developed 
and of the chewing type, but in the adult they become practically useless. 

These insects are of no economic importance except perhaps to a 
very slight degree as scavengers in the water, feeding on matter that 
might otherwise decay and become objectionable, but their value for 
this is probably small at best. They are fed upon as larvjB and to 
some extent as adults, by fish and some carnivorous insects of other 
groups, and for this reason also may be rated as slightly beneficial. 
At present about 500 kinds are known, but the group has not been very 
thoroughly studied. Many fossil Ephemerids have been found, which 
suggests that the insects are possibly less abundant now than was once 
the case. 



CHAPTER XIII 
THE ODONATA 

The Odonata are such large and noticeable insects that they have 
received many common names, such as dragon-flies, snake-doctors, 
devil's darning needles, snake-feeders, etc. They are most plentiful 
near water, as in this they spend their early lives, though the larger 
and more powerful members of the group are frequently seen flying high 
in the air and at some distance from their more usual habitat. 

The dragon-flies have rather long, slender bodies, the abdomen being 
less shortened by the fusion and telescoping of its segments than in 
most insects. The head is large, generally rather spherical, though con- 
cave behind, and a great part of its surface is occupied by two very large 
compound eyes, each of which in some species, contains more than 
30,000 facets. As these insects are carnivorous and capture their prey 
as it is flying, the advantage of large eyes which are also because of the 
curvature of the surface of the head, capable of seeing in almost every 
direction, is evident. There are also three ocelli. The antennae are 
short and not very noticeable. 

The mouth parts, which are of the chewing type, are large and well 
developed. The food appears to be captured by the legs and held by 
them while it is being eaten. 

Four wings are present, all of about equal size, though the hinder 
pair are somewhat larger except in the section known as the Damsel- 
flies. The main veins are stout and are connected by many cross-veins. 
Near the middle of the costa of each wing is a slight notch called the 
nodus, at which point there is a particularly stout cross-vein. When at 
rest the wings are held either nearly vertical over the body (damsel-flies) 
or extended laterally, much as in flight. The metamorphosis is by pro- 
gressive changes at times of molting, and though the nymph can hardly 
be said to ever greatly resemble the adult, development may be con- 
sidered as being by an incomplete metamorphosis. 

The Odonata may then be characterized as: 

Insects which as adults usually have long, slender bodies, large heads and 
large eyes: wings four, membranous, the hinder pair as large or larger than 
the Jront pair, and each has near the rniddle of its front margin a notch, 
somewhat resembling a joint, called the nodus: mouth parts for chewing and 
well developed. Metamorphosis incom,plete. 

There are two groups of dragon-flies. In one the insect is slender, 
the two pairs of wings are of about equal size, and when not in use are 

68 



THE DON ATA 



69 



held almost vertically above the body (Fig. 39). These insects are often 
called damsel-flies. In the other group the body is stouter and propor- 




FiG. 39. — Damsel-fly {Lcstes uncata Kirby) showing position of wings when at rest. (After 
Necdham, N. Y. State Mus. Bull. 68.) 




Fig. 40. — Dragon-fly (Anax Junius Dru.). Natural size. {Original.) 

tionally shorter, and the wings when at rest extend out horizontally at 
the sides of the body (Fig. 40). 



70 



Al'PLIED ExroMouxn' 



The bodies of dragon-flies are often biilliautly colored, and in some 
cases covered with a '"bloom," giving them a whitish appearance (Fig. 
41). The adults feed on practically almost any tiying insects smaller 
than themselves which they may capture during their flight. Flies and 




Fig. -41. — Dragou-fly (,Flathcmis lydia Dru.) showing ■"bloom" ou abilomen. About 

natural size. {QrifjiualA 

mosquitoes form a favorite food, and the attempt has been made to 
"tame" dragon-fiies and keep them in houses on this account, but with- 
out success. They are very voracious, one specimen having been known 
to consume 40 house-fiies in less than two houi*s. 

I\Iany dragon-tlies fly very swiftly either in direct lines or making 
sudden changes of direction while hunting their prey, and are perhaps 




Fk;. 42. 



-Nymph of a Dragon-fly with mask oxtcudod forward. 

(Original.) 



Enlarged one-third. 



unequalled in this regard by any other insects. They also mate in the 
air. The eggs are laid either in the water, attached to water plants, or 
in the stems of plants under water. In the latter "case they are laid singly 
but otherwise they are usually in clusters containing either a small or a 
large number of eggs. 

The eggs may hatch after a few days, or if laid in the fall, may not 
produce n^'Tnphs until the following spring. The young nymphs stay 



THE O DON ATA 71 

at the bottom of tho water and are carnivorous, feeding on larger and 
larger animals as they grow, individuals of the largest species attacking 
small fish in some cases, though the bulk of their food is undoubtedly 
the aquatic larva3 of insects. They lie on the bottom waiting for their 
prey to come within reach, and when it is near enough they thrust out 
the under-lip (labium) and seize it (Fig. 42). This labium has been 
remarkably developed from its usual form, l)eing flrawn out into two long 
pieces with a pair of jaws or claws at the end. When not extended the 
piece connected at one end with tlie head is bent backward undei- the 
body, while the second piece, hinged to the other end of the first, extends 
forward so that its front end with the jaws lies near the front of the head, 
which it somewhat conceals, and this has led to calling the structure a 
"mask." When this is extended foiwaixl it reaches out more than twice 
tin; length of the head, thus enabling the nymph to capture animals which 
are not very close to it. 

Breathing in the nymphs of the damsel-flies appears to be, in part at 
least, by means of long and rather large, tracheal gills at the end of the 
abdomen, which ai-e also used for swimming. In the other section of 
the Oi-der, the gills are found in the I'ectuni, into whicli water is drawn, 
bathing the gills there, aftei' wliich it is expelled, and if this is done (piickly 
the recoil carries the nymi)li forward, tlnis pi'oviding one means of 
locomotion. 

Molts are frequent, and when full-grown the nymph crawls out of 
the water and molts for the last time, whereupon the wings grow to full 
size and the adult insect is produced. Some diagon-flies have two 
generations a year or possi})ly even more, while in other cases more than 
a year is necessary to a generation, but one each season is the usual 
condition. 

Despite tradition and their bad reputation, dragon-flies are in no 
way injurious to man, not stinging — they have nothing to sting with — 
nor biting to such an extent as to cause the slightest pain, their jaws 
being too weak to even break the skin. They are beneficial insects 
both as young and adults, so much of their food consists of injui'ious 
insects such as flies, mosquitoes, etc., while the injury they cause by 
feeding on fish is usually so slight as to be negligil)le. 

Dragon-flies are sun-loving animals, concealing themselves during 
dark, cloudy weather Between 5,000 and 10,000 kinds are known, and 
the greatest number of these occur in the warmer regions. Fossil dragon- 
flies or insects resembling them are numerous, and some of them were 
very large, one measuring more than two feet from wing-tip to wing-tip. 



CHAPTER XIV 



THE PLECOPTERA 



The most usual common name for the Plecoptera is the Stone-flies. 
They range from small to good-sized insects whose bodies are quite long, 
flattened and with rather parallel sides. The wings are nearly always 
well developed and with many cross-veins, though in a few cases they are 
very small and in some species the cross-veins are few. Considering 
only the more usual condition, the fore wings extend well behind the 
end of the body when closed and have a considerably smaller area than 
the hind wings which are so broad that when they are at rest upon the 
upper side of the body they must be folded lengthwise into plaits to 
reduce them to the necessary width (Fig. 43). 




Fig. 43. 



-Adult Plecopteran {Pteronarcys regalis Newm.)- 

Folsom.) 



Slightly reduced. {From 



The antennae are long and composed of many segments. In most 
members of the group a pair of cerci is present at the end of the abdomen. 
The mouth parts are of the chewing type but are generally so weakly 
developed as to be practically useless. The larvae live in water and do 
not differ greatly in appearance from the adults. 

The group may be described as follows: 

Insects which as adults have four membranous wings, usually longer 
than the body, and generally with many cross-veins. Hind wivgs larger 
than the front ones and when at rest folded lengthwise and lying, covered by 
the front pair, on the abdomen. Antennce long: a pair of caudal cerci 
usually present: mouth parts for chewing but generally poorly developed. 
Metamorphosis incomplete. 

72 



THE PLECOPTERA 73 

Adult stone-flies are most numerous near streams and particularly 
those with a rapid current. The eggs which are often several thousand 
in number, are laid in the water and the nymphs locate on the underside 
of stones. Some breathe through the surface of the body. Tracheal 
gills, when present, are not leaf-like as in the May-flies but are tufts of 
numerous short, thread-like structures containing tracheae, a tuft or 
bundle just behind each leg, on the underside, and also on the first two 
abdominal segments. When fully grown the nymphs leave the water 
and molt for the last time on land. They feed on small insects, probably 
largely May-fly nymphs, and possibly on vegetable matter (diatoms) 
and are themselves a favorite food for fish. 

Some species of stone-flies appear in enormous numbers just as the 
ice is breaking up in the streams, in the northern United States, and others 
are found on the snow even earlier in the season, on warm days. In 
general the group is without economic importance, but a few kinds of 
adults have recently been observed injuring the buds and foliage of fruit 
trees as these first develop, in the northwest, and in these species the 
mouth parts are much more strongly developed than in the others. 
Only 2,000 to 3,000 species are known. 



CHAPTER XV 
THE EMBHDINA 

This is a small group of insects, only about 60 species having been 
described. They live in warm climates either under stones or on plants 
in crevices of the bark or elsewhere, spinning silken tunnels in which to 
live. The largest species known is less than an inch long (Fig. 44). 

The wings are generally (always?) present in the males and absent 
in the females. The tunnels appear to be formed at least partly for 
protection, but perhaps also to aid in preserving moisture, for when dry 





i 


1 


/ 
i 


^ 




') 


( 



Fig. 44. — Emhia major Imms, about 13^2 times natural size. 

Linn. Soc. Lond. 1913.) 



(^Reduced from Imms. Trans. 



weather comes on they are carried deeper into the soil in the ground- 
inhabiting forms. The silk appears to be produced by glands located 
in the tarsi of the fore legs — something unparalleled elsewhere among 
insects. The mouth parts are of the chewing type. 

The food of these insects is probably vegetable matter, but the injury 
they do to plants, as thus far reported, is not great. Even where they 
are most abundant they are seldom seen except by those looking for 
them. A few fossil specimens belonging to this group have been found 
preserved in amber. The Embiids appear to be more closely related to 
the Plecoptera than to any of the other orders of insects. 



74 



CHAPTER XVI 
THE ORTHOPTERA 

The Orthoptera is a large group of insects containing over 10,000 
species. Many of them are very large and striking in appearance and 
common names have been given to different families in the order, but 
none to it as a whole. 

The insects of this order are so diverse in structure, appearance and 
habits that it is difficult to give distinctive characters, but they all 
have well-developed chewing mouth parts. The majority of them have 
four wings, the front pair being slightly thicker than the others, somewhat 
leathery in texture, and overlapping more or less when folded. The 
hind wings are almost always larger and fold in plaits. In many of the 
group, however, the wings are lacking or very small, in which case it is 
difficult to determine whether the insect is an adult or a nymph, without, 
or with only partially developed wings. 

In some of the families the hind legs are much developed and the 
insects have the power of jumping: in others this is not the case and 
walking and running are their methods of locomotion on the ground. 
On this basis the Order has often been divided into two sections, Cursoria 
or running Orthoptera, and Saltatoria or leaping Orthoptera. 

The Orthoptera may be defined, despite the difficulties above indi- 
cated, as: 

Insects which when adult have mouth parts for chewing; usually four 
wings, the front pair thicker than the others; the hind pair larger and folded 
in plaits when at rest. A pair of cerci is always present. Metamorphosis 
incomplete. 

Many students of the group are of the opinion that the insects 
included in this order should really be placed in two or three, but at 
present such a separation seems hardly advisable. Most of the families are 
quite distinct. The group is frequently divided into eight or ten families, 
but for the purposes of this book, six will be considered. These are: 

( Blattidae, Roaches. 

Cursoria \ Mantidse, Mantids. 

I Phasmidse, Walking Sticks. 

r Acrididse, Locusts and Short-horned Grasshoppers. 

Saltatoria i Tettigoniidse, Long-horned Grasshoppers and Katydids. 

^ GryllidsB, Crickets. 

75 



76 APPLIED ENTOMOLOGY 

Family Blattidae (The Roaches) 

These insects are known by a variety of common names such as 
roaches, cockroaches, water-bugs, and black-beetles. The group is 
primarily one living in warm countries with many kinds living in houses, 
and many more, some of them several inches in length, occurring wild. 
In more northern climates only a few are wild and four are household 
pests; these last when adult ranging from less than' an inch to nearly 
two inches in length. In the north the wild species are found under 
logs and stones and never enter houses. They are pale brown and the 
winged adults are an inch or slightly more in length. 

Roaches are generally brown or dark colored, though some are 
green. They are broad and flattened, with the head bent under the body 
so that the mouth opens backward and the eyes look downward. The 
antennae are long, slender and of many segments. Wings are usually 
developed in the adults and the hinder pair fold once. The mouth 
parts are strong and the legs are long, and bear many spines. Roaches 
are active at night, hiding in dark places such as cracks and crevices 
during daylight, and can run rapidly. 




Fig. 45. — Egg case of American Roach: a, side; b, end view. Both considerably enlarged. 
{Modified from U. S. D. A. Farm. Bull. 658.) 

The household pests of this group consume foods and food materials 
freely; gnaw woolen goods, leather, and anything which has paste 
on it, and thus often injure book bindings; in fact they are practically 
omnivorous. Besides eating, they leave a disagreeable "roachy" odor 
which spoils food where they have been. When abundant they become 
very troublesome and vigorous measures must be taken for their control. 
They lay their eggs in packets, the number per packet varying with the 
species, and the outside case is horny in nature (Fig. 45). This case 
may be carried around partly projecting from the body of the parent for 
several days or even weeks. The young are active, feed freely and molt 
several times, but it is doubtful if there is more than one generation a 
year, at least in the northern United States. 

House Roaches 

The German Roach {Blatella germanica L.). — This insect, often 
called the Croton bug, came from Europe and is generally the most 
common of the house roaches in the eastern United States (Fig. 46). 



THE ORTHOPTERA 



77 




Fig. 46. — German Roach or Croton Bug (BlatellagernianicaL.). c, egg case much enlarged 
e, adult, natural size;/, adult carrying egg case. {From U. S. D. A. Farm. Bull. 658.) 




Fig. 47.— American Roach {Periplaneta americana L.) adults: a, from above; b, from 
beneath, about natural size. (Modified from U. S. D. A. Farm. Bull. 658.) 





Fig. 48. Fig. 49. 

Fig. 48. — Australian Roach (Periplaneta australasiw Fab.). Adult, about two-thirds 
natural size. (Reduced from, U. S. D. A. Farm.. Bull. 658.) 

Fig. 49. — Oriental Roach (Blatta orientalis L.) adults about two-thirds natural size: 
a, female; b, male. (Reduced from U. S. D. A. Farm. Bull. 658.) 



78 APPLIED ENTOMOLOGY 

The adult is from one-half to three-fourths of an inch long, pale brown 
with two darker brown stripes. It is very active and increases in 
numbers very rapidly. 

The American Roach (Periplaneta americana L.). — This is the largest 
of the house roaches, being from one and one-fourth to one and one-half 
inches long when adult. It is brown, darker than the German roach, 
and has a more or less definite yellow band around the margin of the 
pronotum (Fig. 47). It is a native of the warmer parts of this country 
but has spread north and is now abundant everywhere except in the 
most northerly states. 

The Australian Roach {Periplaneta australasice Fab.). — Somewhat 
smaller and apparently broader than the last, and with the yellow 
band around the prothorax brighter, and a yellow streak on the costa 
of the fore wing extending part way toward the tip (Fig. 48). It is 
particularly common in the Southern States. 

The Oriental Roach (Blatta orientalis L.). — This insect is the "black- 
beetle" of Europe. It is almost black and the wings in the adult male 
are considerably shorter than the body, while In the female they are 
hardly more than stubs. It is a stout-bodied insect, quite generally 
present in the eastern, southern and central United States as far west 
as the great plains, and is the most common species in Europe (Fig. 49). 

Other kinds of roaches are occasionally found in the Northern States 
brought there in bunches of bananas or with other southern fruits, but 
they do not appear to be able to live long in the colder climates. 

Control. — Various materials are more or less effective as roach killers, 
but the best of these is commercial sodium fluorid. It may be mixed with 
flour or some other inert substance, but nothing is gained by this except 
a reduction of the cost of treatment and the killing may not be as rapid. 
The powder is thoroughly dusted where the roaches occur, particularly 
in their hiding places, using a dust gun or blower. The insects which 
by crawling or in other ways get the dust on their antennae or legs, clean 
these parts by drawing them between their mouth parts so that the 
powder enters the mouth and probably acts through the alimentary 
canal. 

• Family Mantidae (The Mantids) 

The Mantids are usually quite large insects with bodies much longer 
than wide, and a broad head which moves very freely upon the thorax. 
The prothorax, with few exceptions, is very long, and bears legs adapted 
for grasping the prey and which are well provided with spines, the in- 
sects walking on the other four. In nearly all members of the group 
the wings are well developed, the hinder pair larger and folding in 
plaits when at rest with the other pair on the back of the abdomen. 
They are often called Rear-horses, Devil-horses, Soothsayers, Praying 
Mantids or Mule Killers. 



THE ORTHOPTERA 



79 



The Mantids are carnivorous, feeding on flies and other insects and 
are therefore beneficial. Fifteen to twenty kinds occur in the United 
States, particularly in the south, but the group is mainly found in tropical 
countries where it reaches its greatest development and includes some 
remarkable forms. 

Mantid eggs are laid in cases composed of a thick material which 
quickly dries. They are usually laid in the fall and hatch the following 
spring. Some of the cases are very noticeable, being an inch or more 
long. They are usually attached to plant stems (see Fig. 51). 




i 


1 



Fig. 50. Fu;. 51. 

Fig. 50. — Common American Mantis {Stauomanlia Carolina L.) waiting for its prey. 
Slightly reduced. {Original.) 

Fig. 51. — Egg case of common American Mantis, natural size. {Original.) 



The most common Mantis {Stagomantis Carolina L., Fig. 50) is found 
as far north as southern New Jersey, Pennsylvania and Ohio. It is about 
two and one-half inches long when adult, green or brown, or a mixture 
of the two colors, and is found not only on plants but also often on 
houses, sheds or in other places where it may obtain its prey. It locates 
in some spot, then raising its prothorax and head somewhat, with its 
fore legs partly extended, quietly waits until an unwary insect comes 
within its reach. When this happens, a quick motion of its fore legs and 
the prey is seized, the spines aiding in holding the insect, which is then fed 
upon. 

In 1897 a Mantid from China {Paratenodera sinensis Sauss.) was dis- 
covered near Philadelphia where it appears to have successfully estab- 
lished itself. It is much larger than the common native Mantis, being 
about four inches long. In 1899 the common European Mantis {Mantis 
religiosa L.) was found near Rochester, N. Y., where it appears to be 
quite common. It much resembles our native form but is slightly larger 
(Figs. 52 and 53). 



80 



APPLIED ENTOMOLOGY 



As these insects are beneficial, attempts have been made to establish 
them in other places, but thus far they do not seem able to withstand 
severe winters, and in the case of the last named species it has until now 





Fig. 52. Fig. 53. 

Fig. 52. — European Mantis {Mantis religiosa L.), natural size, with wings spread. 
(Original.) 

Fig. 53. — Egg case of European Mantis, natural size. (Original.) 

apparently been unable to live north of Ontario, and colonies placed in 
New England have died out. 

Family Phasmidae (The Walking-Sticks) 
The Phasmids are generally called "walking-sticks." Their bodies 
are usually long and stick-like, due largely to their very long and slender 




Fig. 54. — Common Walking-stick (Diapheromera femorata Say) natural size. (Original.) 

meso- and metathoracic segments. Their legs and antennae are also 
generally long, and the 15 to 20 kinds found in the United States 



THE ORTHOPTERA 



81 



are wingless, or with only wing stubs, which adds to their stick-like 
appearance. They are brown or green in color and thus much re- 
semble the twigs on which they rest, or the larger leaf veins. Only 
one species (Diapheromera femorata Say) is abundant except in the more 
southern states, but this is quite generally present (Fig. 54). 

Walking-sticks feed on foliage and when abundant may entirely 
strip many acres of forest trees of their leaves, though this does not 
often happen. Their eggs are laid in the fall, being dropped singly, 
wherever the insects happen to be, and falling to the ground remain 
there until the following spring, or in some cases until the second spring, 
before hatching. Though not laid a 
number together in a case as in the last 
two families, each egg has a case or 
capsule of its own. 

Where forest areas are attacked, no 
entirely satisfactory method of control 
is known. In the case of a few trees or 
plants easily accessible, spraying with a 
stomach poison is sufficient to prevent 
farther injury. 

This group is mainly a tropical one, 
over 600 kinds being known, very variable 
in size and appearance. One species has 
a body nine inches or more in length, 
and with its front legs extended forward 
and its hinder ones backward — a position 
it often assumes — may measure sixteen 
inches or even more, while its body has 
a diameter of less than one-quartor of 
an inch. In the tropical forms wings are 
often present, and in some cases colored and marked to resemble leaves. 
This resemblance is increased in Pulchriphyllium scythe Grsiy (Fig. 55), 
found in the East Indies, by leaf-like expansions of the femora and tibiae 
and of the body itself. 

The insects belonging to the three families of this order, treated thus 
far,- are all walkers or runners (Cursoria). Those now to be considered 
are leaping forms (Saltatoria), the hind legs being longer than the others 
and provided with powerful muscles. Their heads are generally strongly 
hypognathous, the mouth being directed downward and in some cases 
even a little backward. Sounds sometimes called musical are produced 
by most members of these families. 

Family Acrididae (The Grasshoppers) 
The insects belonging in this group are commonly called grasshoppers. 
A few kinds when adult migrate, often in such enormous numbers as to 




Fig. 55. — A Tropical Leaf-insect 
(Pulchriphyllium scythe Gray) about 
half natural size. (Original.) 



82 



APPLIED ENTOMOLOGY 



look like clouds in the sky. These migrating species are sometimes 
spoken of as locusts. 

Grasshoppers are feeders on grass and vegetation in general and 
are injurious, the amount of injury they cause varying with their 
abundance. Their antennae, shorter than the body, and their tarsi, 
consisting of only three segments, quickly distinguish them from the 
related family Tettigoniidse. The pronotum is extended backward 
somewhat, and down on the sides of the prothorax almost to the base 
of the fore legs. In the female there is a short, stout ovipositor com- 
posed of four parts, and the rather narrow fore wings, usually somewhat 
leathery in texture, cover the large, delicate hinder pair when these, 
folded in plaits, are at rest above and along the sides of the body. 

Most grasshoppers lay their eggs in the ground, usually in the fall, 
and these hatch the following spring. The female works its ovipositor 
into the soil a short distance, then pushes apart its four pieces and 
deposits its eggs in a cluster containing from twenty-five to perhaps 





Fig. 56, Fig. 57. 

Fig. 56. — Two-striped Grasshopper {Melanopliis bivitlatus Say) laying egg.s. {Rcduad 
from U. S. D. A. Farm. Bull. 747.) 

Fig. 57. — Sao, or "Egg-pod" of Grasshopper eggs in the ground. About natural 
size. {Reduced from U. S. D. A. Farm. Bull. 747.) 

five times that number of eggs, covered by a fluid which hardens and forms 
a sort of protecting case (Figs. 56 and 57). The young on hatching, 
work their way out of the ground and feed, molting several times and 
becoming adult after 2 or 3 months. 

Only a few of the kinds of grasshoppers found in the United States 
are sufficiently migratory in their nature to deserve the name "locust." 
During the period between 1860 and 1880, however, and to some extent 
since, inhabitants of the states west of the Mississippi River have at 
times suffered the entire, or almost entire loss of their crops by the 
ravages of swarms of the Rocky Mountain locust (Melanopliis spretus 
Thom.) which, breeding in immense numbers on the eastern slopes of 
the Rocky Mountains, upon maturity migrated eastward for food, and 
stripped everything where they alighted. Settlement of these breeding 
grounds, and cultivation, destroying the eggs, has largely put an end to 
these migratory flights, but occasionally grasshoppers occur in destruc- 



THE ORTHOPTERA 



83 



tive abundance, not only in the West but in all parts of the country 
wherever they become so plenty as to lay large numbers of eggs in ground 
not cultivated, such as pastures. Under such conditions, a sudden, 
more or less local outbreak of these insects may take place in the spring, 
•the damage being caused in these cases, at first by the feeding of the 
nymphs, and later, if nothing is done, by the adults. 

Aside from plowing, harrowing or disking land in which grasshoppers 
breed, before the eggs hatch in the spring, the most successful method 
of control when they appear in sufficient abundance to make treatment 
necessary, is the use of a poisoned bait. There are various formulas for 
this, but there is no marked difference in the results in most cases. 

One in general use is: wheat bran, 25 lb.; Paris green or white arsenic, 

1 lb.; oranges or lemons, 6 fruits finely chopped; low-grade molasses, 

2 qt. Mix the bran and poison well, dry; then add the chopped fruit 
and its juice; finally add the molasses and stir thoroughly. Enough 
water — 2 or 3 gal. — should be added to this so that each flake of the bran 
is sufficiently moist to have some of the poison adhere to it, and also 
take up the flavor of the fruit and molasses, yet not enough to make 
the flakes stick and prevent sowing broadcast. This amount of material 
should be sufficient to spread over two or three acres. In the Eastern 
States and wherever the air is moist, the best results are obtained by 
spreading the bait very early in the morning. In arid or semiarid 
regions, 3 or 4 gal. of water may be needed in the mixture, which should 
be distributed toward night. 

A form of poisoned bait, known as the modified Criddle Mixture, 
substitutes a half barrel of fresh horse droppings for the bran and 
omits the molasses. The only advantage with this is that it can be used 
where bran is too expensive or hard to obtain. 





Fig. 58. Fio. 59. 

Fig. 58. — Red-legged Grasshopper (Melanoplus femur-rubrum De G.) about natural 
size. (Reduced from U. S. D. A. Farm. Bull. 747 ) 

Fig. 59. — California Devastating Grasshopper (Melanoplus devastator Scudd.) about 
natural size. (Reduced from U. S. D. A. Farm. Bull. 747.) 

There are many kinds of grasshoppers in the United States. Among the 
more abundant and therefore injurious species, may be mentioned the red-legged 
grasshopper {Melanoplus femur-rubrum De G., Fig. 58), about an inch long, its 
hind tibige bright red; the California devastating gra.sshopper {Melanoplus 
devastator Scudd., Fig. 59), a little smaller, found in the Western States; the 
differential grasshopper {Melanoplus differentialis Thom.), about an inch and a 



84 



APPLIED ENTOMOLOGY 



half long, present nearly everywhere, but rare in the East; the two-striped 
grasshopper {Melanoplus bivittatus Say) about the size of the last, with two 
yellow stripes along its back, generally distributed except in the South Atlantic 
States (Fig. 60); the lesser migratory grasshopper {Melano-plus atlanis Riley) 
about an inch long, found nearly everywhere in the United States and frequently 





Fig. 60. Fig. 61. 

Fio, 60.— Two-striped Grasshopper {Melanoplus biviltatus Say) about natural size. 
(Reduced from U. S. D. A. Farm. Bull. 747.) 

Fig. 61.— Lesser Migratory Grasshopper {Melanoplun atlanis Riley) about natural 
size. {Reduced from U. S. D. A. Farm. Bull. 747.) 

seriously abundant west of the Mississippi River (Fig. Gl); and the clear-winged 
grasshopper (CamnulapellucidaScudd.) which though small is often very injurious. 
It is found in all the northern United States and has its hind wings clear and 
almost colorless, while its fore wings are spotted with brown. All of these 
species attack various cereal and forage crops. 




Fig. 62. — Florida Lubber Grasshopper {Dictyophorus reticulatus Thunb.) about natural 
size. {From U. S. D. A. Farm. Bull. 747.) 



In the Southern and Western States are large, short-winged grasshoppers 
which are very stout, and from their appearance and clumsy movements are 
called "lubber grasshoppers" (Fig. 62). They attack grass, alfalfa and other 
crops. 

The Carolina grasshopper {Dissosteira Carolina L., Fig. 63), one and a half 
inches or more in length, is gray or brown, varying somewhat with the color of 
the ground where it hves. It is most noticeable along roads and when startled 
into flight its black hind wings with yellow margins, and the crackling sound 
often produced at such times are sufficient to attract attention. It is found 
throughout the entire United States. 



THE ORTHOPTERA 



85 



In one section including the smallest grasshoppers, generally called "grouse 
locusts," some of which are less than half an inch in length, the pronotum is 
extended back to, or even beyond the end of the abdomen and the fore wings 
are reduced to mere stubs. Two common species are shown in Fig. 64. 

The hind wings of grasshoppers are often brightly colored, yellow, 
red, or black. The legs also often show bright colors. 




Fig. G3. — Carolina Grasshopper {Di!isotitt.ira Carolina Say) uaturai size. {Original.) 

The sounds produced by grasshoppers are made in one or the other 
of two ways. In some species the hind legs are drawn up and down 
across the fore wings, ridges on the inner face of the femur scratching 
against a heavy vein on the wing and giving a rasping sound. In others 
the sound is produced wdiile flying. Here the front edge of the hind wing 




Fig. 64. — Two types of "Grouse Locusts," natural size. {Original.) 

is struck against the under surface of the fore wing, making a short, 
sharp sound, which, quickly repeated, gives a kind of "crackling." 
Apparently the organs of hearing are located on each side of the body 
just above the base of the hind leg. Each is a rather large, smooth disk, 
suggestive of an ear drum membrane, connected by nerve fibers with a 
small ganglion which in turn connects with the main nervous sj^stem. 



Family Tettigoniidae (The Green Grasshoppers and Katydids) 

A part of the insects of this family are called green grasshoppers, 
long-horned grasshoppers, or meadow grasshoppers, while others are 
the katydids. Their tarsi consist of four segments. Most of them are 
green in color, and all have antennae longer than their bodies. Some of 
the katydids have broad fore wings and these live among trees and 
shrubs, feeding on the leaves and even on the more tender twigs (Fig. 65), 



86 



APPLIED ENTOMOLOGY 



Others have narrow fore wings and appear to prefer bushes or tall weeds 
and grass as their abiding places (Fig. 66). The meadow grasshoppers 
resemble the narrow-winged katydids but average smaller and are most 




Fig. G5. — Broad-winged Katydid {Amblycorypha rotundifolia Scudd.), natural size. 

(Original.) 

abundant in fields and pastures, particularly where the grass is thick and 
tall. In most members of the group the ovipositor is long or at least 
large enough to be quite noticeable. 




Fig. 66.— Narrow-winged Katydid (Scuddcria curvicauda De G.). slightly enlarged. 

(Original.) 



Some of the Tettigoniids are wingless and come out only at night, 
hiding under logs, stones or in dark places during the day. They are of 
various shades of brown or gray, and the species found in different parts 
of the country vary much in appearance (Fig. 67). They are called 
"wingless grasshoppers," "camel crickets," "shield-backed grasshop- 



THE ORTHOPTERA 



87 



pers," "Jerusalem crickets," etc., according to their kind and the local 
usage. 

Sound in this family is produced by the males. The base of the 
fore wing is modified, not necessarily in the same way in all the species, 
but in such a manner that rubbing these wings together will produce a 
sound. The organ of hearing is a small, oval membrane located near 




Fig. 67. — "Wingless Grasshopper," natural size. (Original.) 

the base of the tibia on each side of the front leg. Inside the membrane 
is a hollow space or resonance chamber, and a nerve supply. The sounds 
made by these insects are produced chiefly toward evening and at night, 
though in dense woods they may sometimes be heard earlier in the day. 
The members of this group are rarely serious pests, though katydids 
have been known to injure orange groves and presumably some forest 




Fig. 08. — "Western Cricket" {Anabrus purpiirascens UhL), slightly enlarged. 

Gillette.) 



(.ifter 



trees suffer more than is generally realized, when these insects are abun- 
dant. One exception to this general unimportance of the family is met 
with in the case of the wingless species known as the "western cricket" 
(Anabrus purpurascens UhL, Fig. 68), which in some of the Western 
States may be a serious crop pest. 



88 



APPLIED ENTOMOLOGY 



Family Gryllidae (The Crickets) 

The crickets are familiar insects, often seen walking or leaping over 
the ground. 

In this family the wings are frequently reduced or absent, but when 
present the front pair are so bent that one part lies flat over the back 
while the other lies against the side of the body when not -in use. The 
antennae are in most cases, longer than the body. A convenient group- 
ing of these insects is into the field crickets, the mole crickets and the 
tree crickets. 




Fig. 69 



. — Common Black Cricket (Gryllus abbreviatus Serv.), natural size. {Original.) 



The sounds are produced by the wings of the males, which are rubbed 
over each other. On one wing is a strong vein which bears cross ridges, 
while on the other is a thickened area. These two parts (termed file and 
scraper by Comstock) when rubbed together cause the sound. Ears in 
crickets are located as in the last family, on the fore legs, but the two on 
the same leg differ somewhat in appearance. 

The common field crickets (Fig. 69) are black or brown, and a long 
ovipositor is present in the females. They are rather indiscriminate 
feeders, consuming either vegetable or animal materials, and may even 
be cannibals. In houses they will eat foods but are rarely abundant 
enough to become pests. 

The mole crickets are larger and stouter than the common field 
crickets, and because of their habit of burrowing in the ground are less 
often seen (Fig. 70). They are brown in color and their fore legs are 
broad and flat, forming most effective digging organs. The eyes are 
much reduced and the hind legs not being used for leaping, are not so 
greatly developed as in the other crickets. They prefer rather moist 



THE ORTHOPTERA 



89 



TTgjinji'liliiiliii 



Fig. 70. — Common Mole Cricket {Gryllotalpa borealis Burm.), about natural size. 

(Original.) 





Fig. 71. Fig. 72. 

Fig. 71. — Adult Male Tree Cricket (CEcanihus niveus De G.), .somewhat enlarged. 
{Reduced from N. Y. Agr. Exp. Sta. Tech. Bull. 42.) 

Fig. 72. — Female Tree Cricket ovipositing in a twig. Enlarged al)out one-half. 
(Reduced from N. Y. Agr. Exp. Sla. Tech. Bull. 42.) 




b a 

Fig. 73. — Raspberry canes showing: a, row of egg punctures along the cane, inducing 
cracking open; h, cane split open to show the depth of the punctures. Natural size. 
(Original.) 



90 APPLIED ENTOMOLOGY 

land in which to make their burrows, and feed on plant roots, earth worms 
and insect larvse. The "Changa" (Scapteriscus vicinus Scudd.) of Porto 
Rico attacks the roots of various crops in that island, causing much 
injury, and has recently been discovered along the sea coast of some 
of the Southern States where it attacks cotton and may become a serious 
pest. 

The tree crickets differ greatly in appearance from the field and 
mole crickets, being slender, greenish white and only about half to three- 
quarters of an inch in length (Fig. 71). They occur on trees and bushes 
and attract attention from July till frost by their shrill, steadily repeated 
note or song, beginning as it grows dark and continued through the 
night, the rapidity of the note being so closely related to the temperature 
that by timing the number of repetitions per minute a close approxima- 
tion to the thermometer reading can be obtained. 

The tree crickets are rather serious pests as during the fall the females 
make long rows of punctures in the twigs of trees and in berry canes 
(Fig. 72), laying their eggs in these punctures which usually are nearly 
as deep as the diameter of the twig or cane (Fig. 73). The general 
result is the drying and splitting open of the portion of the plant attacked, 
causing its death, besides providing an opportunity for the spores of 
fungous diseases to enter and attack the plant. Control of these insects 
is at present limited to cutting off and destroying the injured parts of the 
plant, with their contained eggs, before these hatch in the spring. 

A few species of crickets live a semiparasitic life in ants' nests and in 
consequence are so much modified as to show little resemblance to the 
common forms. 



CHAPTER XVII 



THE ISOPTERA 



These insects are commonly called White Ants or Termites, the 
former name being used because though not nearly related to ants, 
they live in colonies and in many of their ways resemble these insects. 

The White Ants, as their name suggests, are whitish in color (the 
winged adults may be brown or blackish). The group is essentially a 
tropical one but some of them are found as far north as Canada. The 




Fig. 74. — Castes of a Termite colony: a, queen; b, male; c, worker; d, soldier. {After 
Jordan and Kdloao, Evolution and Animal Life, D. Appleton and Co.) 

tropical species differ so markedly in many of their ways from the north- 
ern ones that separate descriptions almost seem necessary. In all, 
however, there is a colonial life and a division of the insects into several 
groups or "castes." 

A colony normally consists of one or more males or "kings;" one or 
sometimes several females or "queens" and a variable but generally 
large number of other individuals, nearly always at least, of two castes, 
known as workers and soldiers (Fig. 74). These may be individuals of 
either sex which have not developed to reproductive maturity. During 
a short period of their lives the kings and queens have fully-developed 
wings, four in numl)er, long, narrow and quite similar in appearance, 

91 



92 



APPLIED ENTOMOLOGY 



which when at rest are laid flat upon the back. Near the base of each 
wing is a Hne marking where it will easily break off. The part between 
this point and the body is horny, while the remainder is at most only 
somewhat leathery. At the end of the abdomen is a pair of short cerci. 
Development of the young is by an incomplete metamorphosis. 

The group may accordingly be characterized as: 

Insects living in colonies and of several castes, of which only the kings 
and queens ever have wings. These are four in number, long, more or less 
leathery, narrow, similar, laid flat on the back when not in use, and easily 
broken off near their bases. The bodies of the insects are soft, and usually 
whitish in color. The abdomen has a pair of cerci at its hinder end. Mouth 
parts for chewing. The metamorphosis is incomplete. 

The food of Termites is mainly dead wood, though living trees and 
other plants sometimes suffer from their attacks. Their nests in the 
tropics are made of earth, wood 
which has been chewed up, and 
their excrement. They are often 
prominent objects, sometimes twenty 





Fig. 75. Fig. 7G. 

Fig. 75. — Adult male of a tropical Termite {Termes spinosus Latr.) about half natural 
size. (After Desneux.) 

Fig. 76. — Laying queen of a tropical Termite {Termes gilvus Hag.). Reduced nearly 
one-half. {From Desneux.) 

feet or more in height, and seem to vary in form to some extent ac- 
cording to the species. 

Termites "swarm" at some seasons, enormous numbers of winged 
kings (Fig. 75) and queens leaving their nest at about the same time and 
flying off. After alighting the wings are broken off and each pair of 
individuals turns its attention to the establishment of a new colony. 
In the tropical species which form large nests and have thousands of 
individuals in a colony, the abdomen of the queen gradually becomes 
distended by the developing eggs until this part of the body may become 
several inches long and an inch or more in diameter, so that the insect is 
entirely helpless and unable to move (Fig. 76). The workers which are 
generally blind, provide for the queen, carry away the eggs, feed and 
care for the young, construct the nest, and indeed do all the work of the 
colony. The soldiers are generally regarded as a caste produced for the 



THE ISOPTERA 93 

protection of the colony, but numerous observations which show the 
workers to be better fighters, throw doubt upon the real duties of this 
caste. 

Other castes besides those already mentioned have been discovered 
in different species of Termites, at least 15 having been recognized, though 
not for any one species. In addition to the royal pair, workers and 
soldiers, however, a caste consisting of individuals generally called 
complementary kings and queens or neoteinic members of the colony 
is generally present, at least in the older colonies. This caste is capable 
of reproduction, though less abundantly so than the true queen, and 
appears to be produced to continue the colony after her death. 

The most generally common species of Termite in the United States 
(Reticulitermes flavipes Kol.) except perhaps in the far South and on the 
Pacific Coast, does not appear to form large colonies (see Fig. 74). Its 
nests occur under logs and in them, in fence posts, timbers of buildings 
or other structures, or in tunnels in the ground, though here usually in 
near proximity to wood. Centering here they go out through tunnels, 
always protected from the light, mining in woodwork, honeycombing 
it and leaving only a thin film on the surface to conceal them and shut 
out the light. If necessary to reach the wood they desire, they may 
construct small covered passages over the surface of stone, brick or 
similar materials, through which they pass. They will also attack 
books and papers, pasteboard, leather, etc., if stored in dark and moist 
places. In some cases they attack trees, infesting roots and the heart- 
wood near the base. Citrus trees in the South are often seriously in- 
jured by them. Field crops are also affected, the roots being fed upon, 
and plants in gardens and greenhouses are often attacked, the termites 
sometimes coming up to the benches through covered tubes, in the latter 
location, and working first in the wooden bench sides, and then passing 
to the plants themselves. True queens have seldom been found in the 
nests of this species. 

Control. — To check the ravages of these insects in buildings, bridges 
and other structures, all infested wood should be removed. Founda- 
tions should be of stone, brick or concrete, and as far as possible all 
timbers should be exposed to light and not be so placed as to become moist. 
As these insects must have moisture where they are, dryness is an effective 
protection. Where posts must be set in the ground they should be dipped 
in coal-tar creosote before setting. In general, ventilation and dryness 
should be secured whenever possible, as the best protection against the 
ravages of these insects. 

The Termites are not a large group, probably numbering less than two 
thousand species, but the size of their nests in the tropics attracts atten- 
tion, and their habits and colonial life are of much interest. They appear 
to be most closely related to the Orthoptera. Fossil species are quite 
numerous. 



94 APPLIED ENTOMOLOGY 

About 1913 a group of insects was discovered, living in Ceylon, Java, 
Africa and Costa Rica, which seemed to differ so greatly from those 
already known as to justify placing them in a new order. Those first 
found were minute, wingless, with only vestiges of eyes at most, and a 
thorax as long as the abdomen, Cerci are present. The insects aver- 
age about a twelfth of an inch in length, with legs similar in form and 
used for running. The tarsus consists of only two segments and the 
mandibles are well-developed, the mouth parts being of the chewing 
type. More recent discoveries of these insects in Florida and Texas 
show that the adult females may have well-developed eyes; wings, at 
least in some cases, which they shed like the Termites, and that while the 
head resembles that of the Plecoptera the hinder end of the body resem- 
bles that of the Termites. It is also known that these insects are social 
and generally occur near Termites, though not usually mingled with 
them. They will probably prove to be rather nearly related to the 
Isoptera. 

The order Zoraptera has been established to include these insects, 
but so little is as yet known about them that they have not been treated 
in a separate chapter in this book. 



CHAPTER XVIII 
THE DERMAPTERA 

The insects belonging in this group arc commonly called Earwigs, 
because of a mistaken belief that they crawl into the ears of sleeping 
persons. They are most abundant in warm climates, very few being 
found in the more northern states. Both winged and wingless species 
are known, the wings always shorter than the body and the front pair 
tough, leathery and shorter than the hinder pair. The latter are very 
broad, nearly half-moon shaped, with veins radiating from a point behind 
the costa and about one-third the distance from the base to the apex. 
These wings first fold in plaits like a fan, then twice across to reduce 
their length and thus bring them under the fore wings, the forceps aiding 
in this. At the end of the abdomen is a pair of prominent, horny cerci, 
shaped like forceps, differing in form in the two sexes. The mouth parts 
are well developed and of the chewing type. The order may be char- 
acterized as: 

Insects which when adult are usually rather long and narrow in form; 
with chewing mouth parts and a pair of forceps-like cerci at the end of the 
abdomen. Wings may he absent or present: in the latter case the front 
wings are leathery and shorter than the others which are broad and fold in 
plaits from a center, and in addition fold crosswise. The metamorphosis 
is incomplete. 

Earwigs are not generally of great importance as pests in North 
America, though in the South and on the Pacific Coast, as they generally 
feed on fruits, blossoms and other vegetable matter, they may occasion- 
ally cause some injury. This appears to be more frequently the case in 
Europe than in this country. 

They hide in crevices, among leaves and in the ground in the day time, 
coming out at night to feed. In the northern states the most common 
species is the Little Earwig {Labia minor L.), brownish in color and only 
about a quarter of an inch long. It is sometimes attracted to lights at 
night. A much larger, dark-brown, wingless species {Anisolabis mari- 
tima Bon.), a native of Europe has now reached this country and is 
found on the sea beaches of the Eastern United States, under seaweed 
near high-water mark, probably feeding chiefly on decomposing vege- 
table matter (Fig. 77). 

In 1911 the common European Earwig (Forficula auricularia L.), 
which is about three-quarters of an inch in length when adult, was found 

95 



96 



APPLIED ENTOMOLOGY 



to have established itself at Newport, R. I., and another colony of this 
species was discovered at Seattle, Wash, in 1915 (Fig. 78). Both of these 
colonies are increasing and spreading rapidly. The adults lay their 
eggs in the ground in the fall and the adult females winter there also. 




Fig. 



77. — Adults of ;i Wingless Earwig (Anisolabis maritima Bon.), natural size: a, male; 
h, female. {Original.) 



The nymphs feed on green plant shoots, injuring garden plants and flowers 
during the spring, and later in the season turn their attention to blossoms, 
eating the stamens and bases of the petals. The adults too, feed on 
these and also on dead flies, larvae, and even dead or dying individuals 




Fig. 7S. 



-Males (a) and females (6) of the European Earwig (Forficida auricularia L.), 
about twice natural size. {From U. S. D. A. Bull. 566.) 



of their own kind. Their actual injuries however, are far less serious than 
the annoyance caused by their presence in residences, where they crawl 
over everything at night and hide under chair cushions, dishes, in folds 
of clothing and in all crevices in and about the houses during the day. 



THE DERM APT ERA 97 

Control. — During the spring months the nymphs may be destroyed 
by the use of poisoned bread bait, using 16 lb. of stale bread and 1 lb. of 
Paris green or arsenic. Grind the bread fine and thoroughly mix it with 
the poison; then add water enough to make a mixture which will run 
through the fingers and which, spread broadcast, will scatter in small 
particles. Spread this during the evening over lawns or gardens where 
the insects occur. It may need to be repeated once or twice. Afttr 
the first of July when the earwigs have taken to feeding on blossoms, 
the best treatment thus far found is to spray the plants at night with 
the following contact insecticide: 

Soft potash soap 30 oz. 

Water 96 oz. 

Nicotine sulfate 40 per cent 20 teaspoonfuls 

Dissolve the soap in some of the water by heating, then add the rest 
of the water and the nicotine sulfate, making about a gallon of stock 
solution. For use, mix 1 part of this with 22 parts of water. The spray 
should be a fine mist and be thoroughly applied, to be effective. 

In Europe this earwig is not a serious pest, perhaps being kept in 
check by natural enemies not present in this country. 

The Dermaptera as a whole cannot be considered as a group of great 
economic importance. They have sometimes been regarded as a family 
of the Orthoptera and sometimes as a separate order akin to the latter, 
but recent studies seem to indicate a closer relationship to the Coleoptera 
or beetles. Probably not over 500 species of the group are known. 



CHAPTER XIX 

THE COLEOPTERA 

The Coleoptera or beetles is the largest group of insects and members 
of it are familiar to everyone. Over 175,000 kinds are already known, 
and more are discovered every year. Beetles usually have wings, though 
in some cases they are very small and never used. The front pair are 
hard and horny and are called elytra. They are not used in flight but 
when closed lie flat on the back, covering and protecting the hind wings 
and the rather soft external skeleton of the upper side of the abdomen. 




Fig. 79. — Water Beetle with wings spread. {Fixnn Folsom.) 



In some groups they do not reach the end of the body, and in those in- 
sects the unprotected portion of the abdomen is generally of its usual 
thickness. The hind wings are usually quite large and fold in an irregular 
peculiar way to reduce their size and bring them under the elytra when 
they are not in use (Fig. 79). 

The external skeleton of the beetles is usually harder and thicker 
than in most of the other groups. The mouth parts are for chewing, 
both as larvae and adults, and the jaws are often very powerful. The 
early stages are entirely unlike the adult condition, the members of this 
group undergoing a complete metamorphosis. 

98 



THE COLEOFTERA 99 

The distinctive characters of the group are: 

•Insects which as adults nearhj always have Jour wings, the front pair 
entirely thickened and horny; the hind -pair membranous: mouth parts for 
chewing: body usually rather stout. Metamorphosis complete. 

There is a great diversity in the structure of the antennae in different 
beetles, and also in the form of the legs and number of tarsal segments. 
The arrangement of the skeletal plates around the articulation of the 
fore coxae to the body is also variable and of importance in classification. 

Eggs of the Coleoptera are laid in many kinds of places — on leaves, 
in branches, in decaying matter, water, etc. The larvae which hatch 
are usually called "grubs" except when they bore in wood. Then, as 
with larvae of any order found under such conditions, they are termed 
"borers." They usually have the three pairs of legs which become those 
of the adult, though these are sometimes wanting. Some feed upon other 
animals, some on leaves or wood, some on carrion, and others on various 
substances. After full larval growth has been attained they pupate. 
The pupal shell or skeleton generally covers the surface of the body 
closely, but the wings and legs though lying close to it are covered sepa- 
rately as projecting appendages and not ensheathed by the shell enclosing 
the body proper. Such a pupa case is called a pupa libera, or free pupa. 
In some Coleoptera this condition does not obtain, the pupa shell en- 
closing wings, limbs and body with no projecting appendage sheaths, 
and such a case is called a pupa obtecta (see Fig. 33). 

The beetles are generally divided as a matter of convenience into the 
true Coleoptera (Coleoptera genuina or Coleoptera vera) and the Snout 
Beetles (Rhynchophora), though it is at least doubtful if the latter is a 
natural group. The insects in this section are easily recognized, in most 
cases, by having the front of the head prolonged into a snout which may 
be long and slender — in some cases even longer than the body — or short 
and stout, being sometimes so short as to be hardly noticeable. The 
antennae arise from the sides of the snout and in most cases have a bend 
like an elbow near the middle. The mouth parts are at the end of the 
snout, but the labrum and both pairs of palpi are absent. The insects 
of this group are even more firm bodied than the other Coleoptera. 

The true beetles (Coleoptera vera) have no snout. The mouth parts 
are all present and as a group its members average larger than the 
Rhynchophora: indeed the largest bodied insects known belong here. 

THE TRUE COLEOPTERA (Coleoptera vera) 

This is by far the larger section of the beetles, more than 75 of the 
80 odd families belonging here. They vary greatly in structure, habits 
and food. Many of the families are of little or no economic importance 
and have few members, while others include a very large number of 
species, many of wnich are very destructive. 



100 



APPLIED ENTOMOLOGY 



Family LampyridaB (Fire flies, etc.). — In several ways the insects 
belonging here appear to be among the simplest of the beetles (Fig. 80). 
Their bodies are quite soft as compared with the others; the abdomen has 
been little reduced, seven or eight segments being perceptible, and the 
larvae are quite simple and feed on small insects and other animals such as 
snails, either living or dead. 

Only a few members of the group are often noticed except by ento- 
mologists, but those which attract attention are familiar by the light they 

produce at night, which has given them the 
names "fire flies," "lightning bugs," etc. The 
light is produced by specialized areas of the 
body, frequently at least on the underside of 
the abdomen near its tip. The light itself is 
not persistent but comes in flashes and is dis- 
tinctly yellow in most cases. It is believed to 
be produced by the oxidation of granules in the 
outer layer of the luminous organ, the oxygen 
being supplied by the tracheae, and under 
control of the nervous system. In some species the adult female is 
wingless so that its light appears as it crawls on the ground, and such 
individuals are often called "glow-worms." 

Other insects and animals also have luminous organs, but the lights 
they produce are probably less frequently seen than those made by Lam- 
pyrids, these being widely distributed and very abundant insects. 




Fig. so. — Examples of 
Common Lampyrid Beetles, 
about natural size. 
{Original.) 




i 


1 



Fig. 81. — Common Ground Beetle 
{Harpalus caliginosiis Fab.), natural 
size. (Original.) 



Fig. 82 . — European Calosoma Beetle 
{Calosoma sycophanta L.) and its larva, natural 
size. (Original.) 



Family Carabidae (Ground-beetles). — These insects are active, rimning quickly 
over the ground, and the group is a large one containing many different species, 
over 1,200 of which are found in the United States (Fig. 81). They feed mainly 
at night, hiding by day, and the majority are dark colored or black, though a few 
have bright colors. They are predaceous, both as larvae and adults in most 
cases, though a few have been known to depart from their usual habits and feed on 
berries and seeds. One species (Calosoma sijcophanta L.) has been brought to this 
country from Europe as it feeds to quite an extent on the caterpillars of the Gypsy 



THE COLEOPTERA 



101 



Moth, even climbing trees in search of its prey, and it is now fairly common in 
most of the New England States (Fig. 82). Asa whole, the group is distinctly a 
beneficial one, feeding on injurious insects both above ground and as these enter 
the ground to pupate. 

Family Cicindelidae (Tiger beetles). — The active flight and bright colors 
of many of the tiger beetles, though most of them are small insects, only about 
half an inch long, make the members of this family quite noticeable (Fig. <S3). 
They are sun- loving forms, most common along roadsides and in sandy places. 
When flushed they fly quickly a few yards, then alight and often turn, facing the 
intruder as though watching his movements. Both they and their larvse feed on 
other insects, the larva living in a burrow in the ground and placing itself at the 
mouth of the burrow ready to grasp any unwary insect which may come near. 
The elytra of the adult are usually metallic brown with light-colored marks sug- 
gestive of musical characters or perhaps hieroglyphics, though in some cases bright 
green, purple, or other colors dominate. In the West the largest insect belonging 
to this family {Amhlyckila cylindriformis Say) does its hunting at night, as is also 
the case with certain related forms of the Pacific Coast. 





Fig. 8.3. — Tiger Beetle (Cicindela) , slightly 
enlarged. (Original.) 



Fig. 84. — Dytiscid Beetle {Dytisciis verticalis 
Say), natural size. (Original.) 



Family Dytiscidae (Carnivorous diving-beetles). — Members of this family are 
present in almost every quiet stream and pond. They are oval, rather flat 
beetles, usually black, and good swimmers, the hinder pair of legs being broad and 
somewhat oar-Uke and heavily fringed with hairs (Fig. 84). The antennae are 
thread-like. Whenever they need air, they float up to the surface of the water 
and allow the hinder end of the body to project a little out of the water. Then, 
lifting the elytra slightly, the air enters the space under them and is retained 
there aided by hairs present. The insect can now stay under water until this air 
supply has been exhausted. The larvse, often called "water-tigers, " they are such 
voracious creatures, feed, like the adults, on various water insects and other 
animals, even attacking small fish. Some of this family may be at least an inch 
and a half long. 

Family Gyrinidae (Whirligig-beetles). — These insects swim on the surface 
of quiet water, generally in groups, and go around and around in a "whirligig" 
sort of fashion. They are usually bluish-black, oval in form, and the compound 



102 



APPLIED ENTOMOLOGY 



eyes are so divided that one part of each is directed upward and the other down- 
ward (Fig. 85). They feed on small insects which come within their reach. The 
larvae, living in the water, breathe by abdominal tracheal gills, and are also 
carnivorous. The group does not include many species, but their habit of 
swimming in companies, and their peculiar "gyrating" over the surface attracts 
attention, nearly everybody having noticed them on this account. 

Family Hydrophilidae (Water-scavenger beetles). — The water-scavenger 
beetles occur in the same types of stream and pond as the carnivorous diving 
beetles, which they greatly resemble (Fig. 86). The outline, however, is usually 
a little more elongately oval; the antennae are club-shaped, and in addition to 
other structural differences, they obtain air by raising the head slightly above 






Fig. 85. Fig. 86. Fig. 87. 

Fig. 8.5. — Gyrinid or Whirligig Beetle (Dineutes) , natural size. {Original.) 
Fig. 86. — Water-soavenger Beetle {Hydrous triangularis Say), natural size. {Original.) 
Fig. 87. — Rove- beetle {Staphylinus vulpinus Nordm.), slightly enlarged. {Original.) 



the surface and collecting a film of it over the under surface of the body, where 
it is retained by a close coating (pubescence) of fine hairs. They feed on decay- 
ing animal and plant material for the most part, though sometimes taking to 
living plants and insects. Some species maj^ be about two inches in length. 
They are of little economic importance. 

Family Staphylinidae (Rove-beetles). — This large family in some regards is 
suggestive of the fire flies as the body of the insect in this group is not as hard 
and firm as in most beetles and seven or eight abdominal segments are present 
(Fig. 87). In other ways, however, it differs greatly from the Lampyrids, the 
body being slender for its length, and the elytra short, not nearly covering the 
top of the abdomen, the segments of which are very movable. The insects run 
rapidly, often lifting up the end of the abdomen in a menacing way. Most of 
the thousand or more species found in this country are small, the larger kinds 
seldom being more than an inch long. They are land forms, feeding on decay- 
ing vegetable and animal materials near which, or under stones and wood, 
they are found. They must be considered as beneficial insects, acting as scav- 
engers. 



THE COLEOPTERA 



103 



Family Silphidae (Carrion-beetles). — Most of the members of this family 
are of good size, ranging from half an inch to three times that length. Two 
rather distinct types of insect are common in the group, one (Silpha, Fig. 88) 
having a broad, rather flat body and with the sides of the prothorax very thin. 
These insects average less than an inch in length and the elytra are usually 
black. In the other type {Necrophorus, Fig. 89) the insect is larger, stout, with 
a body more cylindrical, and the elytra generally have dull red markings and 
are frequently shorter than the abdomen. Both types feed on dead animals in 
most cases, and their larvae have the same food, so that the group may therefore 
be regarded as beneficial. It is not a very large family, in the United States 
at least. 





Fig. 88. — C'arrion-beetle (Silpha 
amer icana L . ) , about natural size. 
(Orininal.) 



Fig. 89. — C'arrion-heetle {Necrophorus 
marainatus Fab.), slightly enlarged. 
{Original.) 



Family Dermestidae (Dermestids). — These insects are small, the largest 
common species in this country being only about one-third of an inch long. Most 
of them are rather short, thick-set beetles, covered' with very small scales which 
give them a gray or brown color, with occasional black, white or red scaly areas 
in some casas, produ( ing spots or bands of these colors. They feed on decaying 
substances, but those most imjjortant as pests attack wool, furs, feathers and 
meat, cheese and fats. In some cases the adults feed on pollen and only the larvse 
are destructive. 

The Larder Beetle {Dennestes lardarius L.). — This common insert is fre- 
quently found in pantries on foods, particularly of a fatty nature. The adult 
(Fig. 90) is dark brown, with a pale-yellowish band across th3 elytra near their 
bases, in which are a few black dots. The larva (Fig. 91) is longer and more 
slender than the adult, with numerous, rather long, black hairs; is brown in 
color, and attacks ham, cheese, beeswax, feathers, and almost any material oily 
or fatty in its nature. 

Control. — ^Little can be done in the way of controlling this pest, except by 
cleanliness and close watch of all fatty substances kept in stock, removing and 
destroying the insects whenever they are discovered. Tightly closed receptacles, 
giving no opportunity for the insects to enter, should be used in which to 
keep such substances. 



104 



APPLIED ENTOMOLOGY 



The Buffalo Carpet Beetle {Anthrenus scrophularwe L.). — The adult of this 
insect is a tiny beetle about three-sixteenths of an inch long, mottled black and 
white, with a red line having three pairs of side branches or lobes, down the middle 
of its back (Fig. 92). It is a household pest in the northeastern states and as 
far west as Iowa and Kansas. In Europe, of which country it is a native, it 
does not appear to be of much importance. The beetles appear in the fall and 
may continue to be found in heated houses all winter. The eggs are laid on 
woolen cloth or .clothes, carpets, rugs, furs, feathers or silk, all of these being 
animal products, and the small hairy larvae feed on the materials named. After 
pupation has been completed, the adults appear and are often noticed on windows. 
In the spring months, probably after laying their eggs, the beetles appear out- 
of-doors and feed on the pollen of various blossoms, the Spiraea being a favorite. 






Fig. 90. Fig. 91. Fig. 92. 

Fig. 90. — Adult Larder Beetle {Dermestes lardarius L.) four times natural size. {From 
Herrick's Insects Injurious to the Household. By Permission of the Macmillan Company, 
Publishers.) 

Fig. 91. — Larva of the Larder Beetle, three times natural size. {From Herrick's 
Insects Injurious to the Household. By Permission of the Macmillan Company, Publishers.) 

Fig. 92. — Adult Buffalo Carpet Beetle {Anthrenus scrophularioe L.), nine times natural 
size. {From Herrick's Insects Injurious to the Household. By Permission of the Macmillan 
Company, Publishers.) 



Whether there is more than one generation a season has not been definitely 
settled. Many of the larvae breed in floor cracks under carpets and rugs, on the 
woolen debris there. 

A somewhat similar, closely related beetle, the Black Carpet Beetle {Attagenus 
piceus Oliv.), also of European origin, and dull black in color (Fig. 93), is likewise 
an enemy to the same general class of materials as the Buffalo Carpet Beetle. 
It appears to be a pest farther south than the last-named insect. The larva 
(Fig. 94) is longer and more slender than that of the Buffalo Carpet Beetle, reddish- 
brown, and with a tuft of long hairs at the end of its body. 

Control of Carpet Beetles. — These insects are repelled by the odors of various 
substances, and clothing, furs, feathers, etc., when put away, can be protected 
from their attacks by placing them in tight bags or boxes, together with the repel- 
lent. NaphthaUne ("moth balls") is the most effective for this purpose, and 



THE COLEOPTERA 



105 



the oil in cedar wood is also of value, hence the use of cedar chests for storage 
purposes, these giving some protection as long as their odor lasts. Camphor also 
is a fair repellent. But with all these materials the tendency is to use too little, 
and in such cases the insects are not driven off. Then too, if the food of these pests 
be put away with either eggs or larviE present, the repellent will not prevent the 
larva; from feeding. The best practice therefore, is to fumigate all material 
likely to be attacked, before packing it away, placing it in a tight box and treating 
it with Carbon disulfid for 24 hr. Then add a liberal supply of moth balls and 
close tightly. The fumingation will destroy these pests in any stage in which 





Fig. 93. Fig. 94. 

Fig. 93. — Adult Black Carpet Beetle (Attagenits piceus Oliv.), enlarged nine times. 
(From Herrick's Insects Injurious to the Household. By Permission of the Macmillan 
Company, Publishers.) 

Fig. 94. — Larva of the Black Carpet Beetle, five times natural size. (From 
Herrick's Insects Injurious to the Household. By Perm.ission of the Macmillan Company, 
Publishers.) 



they may be present, while the naphthaline will keep out adults which might 
otherwise enter thereafter. Fumigation of a room or an entire house if necessary, 
with Hydrocyanic acid gas, or sulfur, is also a good treatment, though if the latter 
substance be used its effect upon metals, and on colors in clothes and wallpapers 
should be remembered. Carpets may be steam-cleaned, this killing the pest in all 
stages, and cold storage for furs and feathers at least, if the temperature be kept 
below 40°F. will prevent injury, though not necessarily killing any of the insects 
which may be present. As some of the larvae may be in floor cracks when carpets 
and rugs are infested, these should be treated with kerosene or gasoline. Woolen 
clothing kept in closets during the warmer seasons of the year should be frequently 
brushed out and aired in the sunlight. 

Family Buprestidae (Flat-headed Borers). — This group of beetles 
contains many forms which injure trees by boring in their trunks. 
Others attack berry canes which often show swellings as a result. A 
few are leaf miners or gall makers. The adults are generally stout, 
robust beetles with heads set into the thorax, rather flat backs, and in 
general dark colored but with a metallic luster, though a few are bright 



106 



APPLIED ENTOMOLOGY 



green or other colors. The larvae which bore in trees, are white except 
for a small, yellowish head, and have a large, flattened prothorax and no 
legs. Some of these insects attack pines; others, different forest trees, 
burrowing at first just under the bark in the sap-wood and later in the 
heart-wood. The average life history requires about a year for its com- 
pletion, but if the tree be vigorous the larva is liable either to die or be 
delayed in its development. The adults are fond of the sun and fly 
freely in the daytime. They are often found on flowers. Several hun- 
dred species are known in this country, all of them injurious, the damage 
they do being largely dependent upon the importance of the tree or 
plant they attack. 

The Flat-headed Apple-tree Borer {Chrysohothris femorata Fab.). — 
This is probably the most injurious of the Buprestids. It attacks more 
than 30 kinds of trees and shrubs, generally selecting individuals which 
are not in a healthy condition or are otherwise favorable fi)r their larva?. 




Fig. 95. — Adult Flal>heacled Apple-tree Borer (Chrysohothris femorata Fab.), enlarged 
3\i times. (From U. S. D. A. Farm. Bull. 1065.) 



The beetle (Fig. 95) is about half an inch long, rather broad, dark brown, 
faintly marked with bands and indefinite spots of gray, and having a 
brassy metallic reflection at certain angles. The underside is bronze, 
and under the wings the abdomen is a metallic greenish-blue. It occurs 
almost everywhere in the United States and in Southern Canada, and 
is a serious enemy of fruit trees. 

The beetles appear soon after apple-blossom time and live for several 
weeks. They frequent the sunny side of the trunks and limbs of trees. 
Here the eggs are laid in fine cracks or under small scales of the bark. 
They hatch in from 2 to 3 weeks and the tiny larva (Fig. 96) bores into 
the inner bark, feeding on this and on the sap-wood and grows rapidly 



THE COLEOPTERA 



107 



unless the tree is vigorous, in which case such an outpouring of sap may 
occur at the wound as to kill (drown?) it or drive it into the outer layers 
of bark where it may live for a time, later working back into the sap-wood 
if the flow becomes small enough to permit it. If the larva can feed in 
the sap-wood it will grow to full size, about an inch long, by fall, at this 
time burrowing into the wood to form a pupal cavity in which the winter 
is spent, pupation itself taking place there the following spring and con- 
tinuing several (three to four) weeks, after which the :uhilt beetle escapes. 




Fig. 96.— Flat-headed Apple-tree Borers (larvcB) of various sizes. Natural size. {From 
U. S. D. A. Farm. Bull. 1065.) 

Control. — Vigorous, healthy trees are not generally liable to attack, 
and cultural methods which will insure this condition are important. 
Trees headed low will shade their trunks and the sun-loving beetles will 
go to those exposed to sunlight. Shading trunks exposed to the sunlight, 
by boards cutting off this light, is a protection, as are also poles set in 
the orchard and covered with sticky material to catch and hold the beetles 
visiting them in search of places to lay their eggs. Wrappings of burlap 
or paper extending from the ground to the limbs will prevent egg-laying, 
but should be removed when this period is past. Birds and insect enemies 
aid in controlling this pest. 

Family Elateridae (Snapping beetles; click-beetles; skip-jacks). — 
These insects somewhat resemble the Buprestids when adult but are 
usually more slender, with their sides more nearly parallel, and the 
economic species also lack a metallic reflection. The hinder corners of 
the pronotum are elongated forming sharp points in the majority of the 
group, and the insects are usually some shade of brown or black, though 
the pronotum and elytra sometimes differ in color and the latter are 
spotted in some cases, mottled black and white in our largest common 
species, and some have rather bright colors or markings (Figs. 97 and 98). 
When those insects fall on their backs they are able to throw themselves 



108 



APPLIED ENTOMOLOGY 



into the air by a sudden snap of the body for the purpose of getting onto 
their feet as they alight again, and if this fails at first the snapping is 
repeated. The larvae (Figs. 97 and 98), commonly called wire worms, 
are nearly all slender, yellow or brown, with very hard shells, often glis- 
tening, one sub-family where they are soft-bodied and white forming a 
notable exception to this. The outline of the hinder end is often made 
use of in distinguishing the 
different kinds of wireworms. 
Their food habits have a wide 
range : some feed on decaying 
wood under bark or elsewhere ; 
others on fungi ; several groups 
are carnivorous, and still 
others feed on roots or seeds 
in the ground. 





Fig. 97. Fig. 98. 

Fig. 97. — Wheat Wireworm (Agriotes mancus Say): a, adult, enlarged about five 
times; h, full-grown larva (Wireworm), enlarged about three times; c, side view of last 
segment of larva. {Fro7n U. S. D. A. Bull. 156.) 

Fig. 98. — Corn and Cotton W'ireworm (Horistonotus uhleri Horn) : o, adult, enlarged 
about ten times; b, full-grown larva (Wireworm), enlarged over four times. (From U. S. 
D. A. Bull. 156.) 

One of the largest insects of this family found in the United States 
is the Eyed Elater {Alaus oculatus L.), which is about an inch and a half 
long; the elytra black, finely marked with white dots; and with a pair of 
large, oval, velvety-black spots rimmed with white on the pronotum 
(Fig. 99). The larvae of this insect feed on insects in decaying wood, 
often that of the apple, but are of little economic importance. 



THE COLEOPTERA 



109 



In the South and also in the West Indies and Mexico are species 
of Elaterids {Pyrophorus spp.) which have an oval, yellowish spot near 
each hinder corner of the pronotum (Fig. 100), and also an area on the 
underside of the abdomen close to, and partially concealed by the meta- 
thorax, which are luminous, producing an intermittent, greenish-yellow, 
quite brilhant light, making the insects very noticeable at night. They 
are beneficial, the larvae feeding on white grubs. 

The injurious members of this family are those wire worms which feed 
on seeds and the roots of plants, and there are many kinds which have 

this habit. Some attack wheat; others 
coi'n, and still others feed on cotton, 
grass, potatoes, sugar-beets and other 
crops, doing much damage. Some are 
most abundant in heavy soils containing 





Fig. 99. Fig. 100. 

Fig. 99. — Adult Eyed Elater (Alaus ocidatus L.), about natural size. {From Linville 
and Kelly, General Zoology, Ginn and Company, Publishers.) 

Fig. 100. — A Luminous Elaterid (Pyrophorus .sp.) showing luminous spots on sides 
of pronotum. Natural si^^c. (Original.) 

much vegetable matter, while others prefer high, sandy land. So many 
species of wire-worms are injurious and so unlike are their habits in 
different parts of the country that each kind seems to require treatment 
especially adapted to it. 

Control. — Some general factors in control may, however, be suggested. 
When wireworms are abundant in low, poorly drained land, drainage 
will be of much assistance. When they attack grass roots in great 
numbers, it is desirable in cultivating such places to substitute field peas, 
buckwheat, or some crop not closely related to grass, for the first crop, if 
possible, even though this does violence to the general ideas of crop 
rotation. When sod land is to be planted, plowing it in July and cultivat- 
ing often and deeply the rest of the summer will destroy many of the 
insects. In the South and in arid regions, however, the insects go deeply 



110 APPLIED ENTOMOLOGY 

into the ground during hot or dry weather, beyond reach by cultivation. 
In such cases planting early in the season and forcing the plants ahead by 
fertilizers and frequent cultivation are helpful. As the underground 
feeding period of these insects is from 3 to 6 years, proper treatment 
for a single season will at best give only partial relief, and to obtain the 
most successful control the special habits of the particular species 
concerned should be ascertained, and control measures to correspond 
be adopted. Various methods for the protection of planted seed have 
been tried but the results have not agreed in all cases and further 
studies along this line are needed. 

The Elateridse is one of the most important groups of beetles from an 

economic standpoint, and injurious species occur practically everywhere 

in the United States. Several hundred kinds are known in this country. 

Family Scarabaeidae (Lamellicorn beetles). — This is a very large 

and important family of beetles, containing many pests. The antennae 

in this group have several of the terminal segments 
large, flattened, and broader on. one side, movable 
but generally carried close together. The insects 
are stout and rather short in most cases, and 
the elytra usually do not cover the entire 
abdomen. 

Based on their habits, two sections of the 
family can be distinguished: the scavengers 
which both as larvae and adults feed on decaying 
matter; and the leaf chafers which as adults 
generally consume leaves or flowers, and whose 
Fig. 101. — Egyptian larvae occur in the ground feeding on roots, or 

e a r V i n g of a Secarabseus. • i ■ i 

iOriainai.) ^ decaying wood. 

The Scavengers, though they may be con- 
sidered as beneficial, are not of great importance, but some species 
because of their peculiar habits have attracted attention for centuries. 
The habit referred to is that shown by some of the so-called "Tumble- 
bugs" in connection with egg laying. A pair of these beetles will to- 
gether form a little dung into a ball which they then begin to roll over 
the ground, often for a long distance. Finally they bury it in the 
ground after an egg has been laid upon it, thus providing partially 
decomposed food for the larva. The Sacred beetle or Scarabseus of 
the Egyptians was one of the insects of this group (Fig. 101) and has 
been preserved in their drawings and carvings as a symbolic record 
of their beliefs. The leaf chafers form the larger part of the family. 
Among them are a number of serious pests. 

The June Bugs or May Beetles (PhyUophaga and other genera). — 
This is a group of beetles quite similar both in appearance and habits. 
The adults are generally dark brown and rather glossy above, from half 




THE COLEOPTERA 



111 



an inch to an inch long, and very stout (Fig. 102). They appear 
during the spring months, earlier in the South than in the North, 
flying at night and arc attracted by lights, to which they fly in a clumsy, 
erratic way. They feed at night on the leaves of various trees, often 
entirely stripping them. Different kinds of June bugs appear to prefer 
different kinds of trees for their food. Some species seem to select the 
oak, others the ash, still others the pine. Small birches have been 
completely stripped of their foliage in a single night. In the South two 
species appear to prefer the longleaf pine and whatever the species, 
large areas of timber may be defoliated when the beetles are abundant, 
(hough this seldom appears to be the case in New England. On the 
Pacific Coast too, though June bugs occur, they do not seem to be as 
important as in the interior of the country, particularly in the Mississippi 
Valley and as far north as the Great Lakes. 




Fig. 102. Fig. 103. 

Fig. 102. — Adult "June Bugs," female and. male, natural tuzc. {From U. S. D. A. 
Farm. Bull. 940.) 

Fig. 103. — Full-grown larva (irhi/r ijnih) of "June Bug," natural size. {Original.) 



The eggs of the June bugs are laid in the ground and hatch in a few 
weeks into tiny "white grubs" with brown heads and legs, and soft, 
white bodies which increase in size toward the hinder end. The grub 
(Fig. 103) as usually found when dug up is curled through the greater part 
of a circle and this is very characteristic, only a few other beetle larvsG 
(and those belong in the same family) greatly resembling it. The grubs 
feed during the summer on decaying vegetation and living plants close to 
the surface of the ground but on the approach of cold weather go deeper 
into the ground to pass the winter. The following spring they come up 
near the surface again and now feed on the plant roots, causing in this, 
their second season, the largest injury. In the fall of the second season 
they again go deep into the ground to pass the winter, coming up the 
third spring to feed on plant roots until June or July, when they go down 
a little, though not usually much if any below where they may be reached 
by deep plowing. Here they transform to pupse which become adult 



112 APPLIED ENTOMOLOGY 

after a month or two, but the beetles remain in these underground pupal 
cells until the next (fourth) spring, when they emerge. The length of a 
generation as thus outlined therefore is 3 years, but the progeny of any 
given beetle appearing one spring will appear the spring of the fourth year 
following, i.e., a generation requires 3 years but is present in parts of 4 
calendar years. 

This life history holds for most of the injurious species of June bugs 
in the Central States, through the country east of the Rocky Mountains. 
In the North, however, the life history in some cases at least, requires 4 
years, while in the Southern States 2 years appears to be the normal period. 
Some appear every year though, indicating the existence of three broods 
in those regions where the 3-year life-history exists, but the size of these 
broods is markedly different. Though undoubtedly subject to factors 
which may increase or decrease the size of these broods as years pass, the 
most abvmdant and destructive one at present is that in which the beetles 
appeared in 1917 and 1920, and which will reappear at 3-year intervals 
hereafter, the greatest destruction being caused by the grubs the following 
year. The second brood, the beetles of which appeared in 1918, was not 
of sufficient size to attract much attention by their injuries in 1919 and 
probably will not be important in 1922, while the third brood with the 
beetles in 1919 and their injuries in 1920 was of importance in only a few 
areas. How soon favoring conditions may lead to one of these last-named 
broods becoming large enough to be important, or unfavorable factors 
reduce the importance of the first-mentioned one, cannot be predicted. 

Though white grubs have many natural enemies, including numerous 
mammals, birds and insects, and also several diseases, both bacterial and 
fungous, they are not sufficient checks to prevent considerable injury. 

Control. — Pasturing hogs in fields considerably infested by white 
grubs is a good practice, the hogs feeding on other insects they find in the 
ground, as well. Poultry can be made use of in the same way, but this is 
most effective when the ground is being cultivated. Rotation of crops 
is also of value if used intelligently. Corn and clover are crops in which 
the beetles will not lay eggs freely. Grain fields have many eggs laid in 
them, but if followed by clover the grubs will do little damage. Fall 
plowing before the grubs go down to pass the winter will^destroy many of 
them. This should be done as late before the grubs start down as possible. 
The spring after beetles were abundant the year before, many small grubs 
should be found in cultivating. In this case seed with small grain or 
clover. If large grubs are abundant either in the fall or the following 
spring, plant late if possible, as the grubs finish feeding before July in 
most cases; or plow as soon after July 15 as possible, to break up and 
destroy the pupae. Where beetles are stripping foliage, spraying with a 
stomach poison, standard, or a little above standard strength, is a good 
treatment where conditions are such as to make it practicable. 



THE COLEOPTERA 



113 



In general the treatment can be based on the year the beetles are 
abundant. Sod land broken up that year should be plowed before Octo- 
ber and should not be in corn or potatoes, but in clover, small grain or 
buckwheat the next year, if the farm practice of that region will permit. 
The following year delay planting till as late as possible. Pasture every 
season with hogs in the fall as soon as the crop is out. 

The Rose Chafer {Macrodadylus subspinosus Fab.). — This insect occurs all 
over the Eastern United States as far south as Virginia and Tennessee and west to 
Colorado, being particularly abundant and destructive in sandy localities. The 
adult beetle is about a third of an inch long, rather stout, though less so in pro- 




FiG. 104. — Rose Chafer (Macrodactylus subspinosus Fab.): n, adult beetle; b, larva 
(grub) ; e, pupa; /, injury to leaves and blossoms of grape with beetles at work. Fine lines 
beside a, b, and e, show the true length: /, somewhat reduced. (From U. S. D. A. Farm. 
Bull. 721.) 

portion to its length than are the June bugs, dull yellow, with pale, red legs which 
are long and slender. It appears about the time roses begin to bloom, i.e., in 
May in the South, and in June in the more northern part of its range, and attacks 
a large number of plants. It seems originally to have been a rose feeder: later 
it became a serious pest of the grape and is now destructive to many fruit and 
shade trees and shrubs, and even to garden fruits and vegetables when abundant, 
eating blossoms, leaves and any fruit which may be available during its adult 
condition (Fig. 104). 

The eggs, about thirty in number, are laid a little below the surface of the 
ground, sandy land being apparently somewhat preferred, and these hatch in 
2 to 3 weeks into tiny white grubs somewhat resembling those of the June bugs, 
s 



114 APPLIED ENTOMOLOGY 

These grubs feed on plant roots, particularly those of grass, until quite late in the 
fall, then work down in the ground to below the frost line, where each forms a 
small earthen cell in which to winter. In the spring pupation takes place and 
from 2 to 4 weeks later the adult beetle is produced and digs its way to the surface. 
An adult individual lives about 3 weeks. 

Control. — Stomach poisons will kill the adults in time but thej^ work too 
slowly to save the plants, which are seriously injured before the beetles die. 
In any case, these could hardly be used on flowers as they would at least mar their 
appearance. On grapes and other fruits, arsenate of lead, using 5 lb. of the paste 
in 50 gal. of water or Bordeaux mixture (better), applied very thoroughly as soon 
as the beetles appear, or just before the blossoms open in the case of the grape, 
has given fair results, though a second treatment just after the blossoms fall is 
sometimes needed. With stone-fruit trees the self-boiled lime-sulfur wash should 
be used instead of the Bordeaux. 

Hand picking, though tedious, is effective with plants growing low enough to 
make this method of control practicable, but must be repeated every day to get 
those which fly to the plants from elsewhere, or emerge from the ground later. 
Bagging the clusters of grapes is often practiced where this plan seems worth 
while. Harrowing the breeding grounds of the insect to a depth of three or four 
inches, during the time they are pupae, i.e., the latter part of May for the central 
part of their range, destroys many of the pupse which appear to be very easily 
killed b}^ any disturbance while in this stage. The difficulty with this is to locate 
the areas where they are breeding most abundantly. Light, sandy ground will 
generally prove to be the place for such treatment. 

This insect seems to have a poisonous effect when eaten by small chickens, 
many dying within a day or two after feeding on Rose Chafers. 

On the Pacific Coast several species of Hoplia seem to play much the same 
role as the Rose Chafer does in the East. Their life history does not appear to 
have been worked out but probably does not differ greatly from that of the Rose 
Chafer, and the treatments are practically the same. The beetles of all the 
species range from about one-quarter to one-half an inch in length and are light 
brown, grayish, mottled, or black with brown, orange-yellow or olive, either in 
spots or entirely concealing the black. Grape, rose, greasewood, blackberry, etc., 
are the chief food plants. 

The Green Japanese Beetle (PopiUia japonica Newst.) has recently been 
discovered in New Jersey. The beetles attack the foliage of many kinds of 
plants including fruit trees, small fruits, garden crops and ornamental trees and 
shrubs: the larva? feed on the roots of plants and on decaying vegetable matter. 
The beetle is about half an inch long and somewhat resembles several of our native 
forms. If, in spite of vigorous measures now being taken to eradicate it, this 
insect should become widely distributed, it will undoubtedly become a serious 
pest as it already' is in Japan. 

Many other Scarabseids are occasionally injuriously abundant in 
different parts of the country but can hardly be considered as of nation- 
wide importance. The largest beetles found in the United States also 
belong here and are called rhinoceros beetles. One species, Dynastes 



THE COLEOPTERA 



115 



iityrusli. (Fig. 105), about two and one-half inches long, is greenish-gray 
with black spots on the elytra. The male has a long horn on the head, 
projecting forward and upward, and another projecting forward from the 
pronotum. The female has only a. small tubercle on the head. It occurs 
in the Southern States. In another species found in the West the pro- 
thoracic horn is much longer. 




Fig. 105. — Rhinoceros Beetle (Dynastes iitijrus L.), about natural size. (Original.) 



Family Chrysomelidae (Leaf beetles). — This is the largest family of 
beetles but its members are small, not often being over half an inch long. 
Most of them are leaf feeders, though the larvse of a few are worm-like 
and attack underground stems or roots. Many are serious pests, and 
though almost none are found throughout the entire country, allied species 
working in similar ways, occur. 

In the group as a whole, yellowish elytra with black lines or spots 
seems to be the prevailing color pattern, though of course, with many 
exceptions. Together with the next two families, from which other 
characters separate this one, the third segment of the tarsus is generally 
broad, being drawn out into a lobe on each side, and is covered beneath 
with minute, closely set hairs (pubescent). The antennae are at most, 
of only average length. 

The Colorado Potato Beetle (Leptinotarsa decimlineata Say). — 
This well-known insect was discovered about 1823 by Long's exploring 
expedition to the Rocky Mountains, in the region of the upper Missouri 
River. Its food there was the BufTalo-bur (Solanum rostratum Dunal) 
and the insect was apparently not remarkably abundant, and certainly 
of no economic importance, nor did it become so until civilization, and 
with this the potato, reached that territory. Then a new and satis- 
factory food plant, abundant enough to provide all the insects with food 
became available and the potato beetle increased in numbers and began 
to spread to the East. At first its rate of spread was only about 50 
miles a year but after crossing the Mississippi River this became more 
rapid and it reached the Atlantic Coast about 1874. Since then it has 
spread both northward and southward until it is now found practically 



116 



APPLIED ENTOMOLOGY 




a 

Fig. lOG . — Colorado Potato 
Beetle {Leplinotarsa decimlineata 
Say), slightly enlarged: a, full- 
grown larva (Grub) ; adult Beetle. 
(From Berlese, After U. S. Bur. 
Eut. Cire. 87.) 



everywhere east of the Rocky Mountains where the potato is grown and 
it has also reached the Pacific Coast, It does not apparently thrive 
in the hot climate of the more southerly States. 

The adult beetle (Fig. 1066) is somewhat less than half an inch long 
and about two-thirds this width, its back rather high and rounded. It 
is clay-yellow and has 10 longitudinal black lines on its elytra. The head 
has a black spot above, and the pronotum has a number of irregular spots. 
Winter is spent as the adult in the ground but the insects come out quite 
early in the spring. As soon as the potatoes are up, they begin, to feed 
and soon lay their eggs, placing these on the under surface of the leaves 

in small clusters, an individual laying 500 
or more in all. They are small, yellow 
eggs which hatch in from 4 days to a week 
or more, according to the temperature. 
The grubs or "slugs" as they are often 
called (Fig. 106a) are dull brick-red, soft 
and with fat bodies. They feed for from 
2 to 3 weeks, then go into the ground 
where they pupate for a week or two, after 
which the adults emerge and lay eggs for a 
second generation, the adults of which ap- 
pear early in the fall. This second gen- 
eration of beetles feeds for a time, then in 
September or October enters the ground to pass the winter. 

As the eggs of this insect are not all laid at one time, different ages 
and different stages even, may be found together in the same field. And 
as the adults feed in the spring during their egg-laying period, as do the 
two generations of adults produced during the season, in addition to the 
two generations of grubs which also consume the leaves, the plants are 
being attacked much of the time. 

While the potato appears to be the preferred food of this insect, other 
members of the nightshade family are sometimes attacked, particularly 
the tomato and eggplant. 

Control. — This pest is easily controlled by spraying with either 
of the stomach poisons and as the potato is quite resistant to poisons, the 
strength of the mixture can with safety be somewhat increased above 
that of the standard formula. The chief difficulty in control is that as 
the beetles attack the rapidly-growing plant as soon as it appears above 
ground, the spray should be applied then, while a week later a large 
amount of new growth which has no poison on it will have developed, 
upon which the insects can feed. To avoid this, spraying during the 
period of rapid growth needs to be done more frequently than is the case 
with most plants. Two or three treatments, however, will generally be 
sufficient, and a combination with Bordeaux mixture is advantageous 
where arsenate of lead is the stomach poison used. 



THE COLEOPTERA 117 

On small areas, Paris green dry, mixed with 10 to 20 parts of some 
inert material, dusted over the plants, preferably while the dew is on 
them, is a fair treatment, and this poison as a spray can also be used. 
Arsenate of lead is at present the preferred poison for this pest, however. 

Various birds, skunks, snakes and toads feed on the Colorado Potato 
Beetle to some extent, and it also has numerous insect enemies. 



The history of the development of the Colorado Potato Beetle, from 
an unimportant, even probably a rather uncommon insect, feeding upon 
a plant of no value to man, into one of the most abundant and widely 
distributed of our pests, attacking and seriously injuring an important 
crop, is a suggestive one. In a division of the insects of the United 
States into those which are injurious as regards man and his various 
interests; those which are beneficial, and those which are of little or no 
economic importance either way, we shall find that the last group is by 
no means a small one. How many species in this group are there which 
are potential pests? It is true that the making available of a new food 
plant to which the Colorado Potato Beetle could turn, was probably the 
chief factor in this particular case, but any insect which for some reason 
changes from an unimportant food plant to a crop plant may at once 
become a pest. Thus another Chrysomelid only a little smaller than the 
Colorado Potato Beetle and closely related to it, the Three-spotted Do- 
ryphora {Doryphora clivicoUis Kirby), which feeds on milkweed, is now of 
practically no importance. But if it should change its food to some 
valuable crop plant it would at once become an important addition to 
the list of insect foes man has to combat. Several such cases are al- 
ready known. How many others may appear as the changing conditions 
which always accompany an increasing population and the consequent 
changes in plant population take place, no one can predict. Some species 
of plants once common are rapidly disappearing. As they go, will the 
insects feeding on them go too, or will they be able to find another food 
plant, and will this one be of value to man? The appearance of new 
pests in such ways may come at any time, and the fact that an insect is 
not now a pest should not lead to its being ignored, for it may have great 
potential importance. The Murky Ground Beetle (Harpalus caliginosus 
Fab.) is now mainly a carnivorous beetle, but sometimes, though rarely, 
attacks the strawberry. If it should turn to this latter plant entirely 
for its food, another important pest would be added to our list and lost 
from among our friends. 

Such facts call for as complete a knowledge as possible of the life 
and habits of all insects whether now beneficial or only of no economic 
importance, in order that we may have the knowledge of them and 
their ways which is necessary in case they should become injurious. 



118 



APPLIED ENTOMOLOGY 




The Striped Cucumber Beetle {Diahrotica vittata Fab.). — The com- 
mon Cucumber beetle is found everywhere in this country (of which it is a 
native) east of the Rocky Mountains. It is a small beetle about a fifth of 
an inch long, with a black head, yellow pronotum and three black stripes 
along its yellow elytra (Fig. 107). The insect passes the winter as the 
adult beetle in protected places, probably among dense weed growth. 
It leaves its winter quarters early in the spring, before any of its culti- 
vated food plants are available, and feeds on blossoms of various kinds 
until cucumbers, squashes and the other cucurbits which are its favorite 
food plants are available. It then attacks these and may also seriously 
injure peas, beans, apples, and later in the season, corn. It lays its 
eggs either singly or in clusters, in the ground 
near the stems and roots of the cucurbits, often 
in crevices of the soil, the total number of eggs 
per beetle varjdng from a few hundred to over a 
thousand. The eggs hatch in a week or two, ac- 
cording to the temperature at that time, and the 
grubs feed on the stems and roots. They are tiny, 
white, slender, and resemble maggots more than 
the usual forms of beetle larvae, and when full 
grown, after 2 to 5 or more weeks, according to the 
temperature, are only about three-tenths of an 
inch long. They then soon change to pupae, still 
in the ground, in which stage they remain for 
about a week before the beetles emerge. The life 
cycle therefore varies in length according to the 
temperature, it being perhaps not over 4 weeks in 
the South and 8 in the more northern States. This gives time for 
several generations each season, and though in the North there is 
apparently but one, this number increases farther south until in Texas 
there may be four. 

The destruction caused by these insects when they are abundant is 
often very great. Their first attacks come just when the young plants 
are struggling to establish themselves and the feeding of the adult 
beetles is often sufficient to kill them. Later in the season the beetles 
continue feeding on the leaves and stems, reducing the vigor of the plant 
and its productiveness, and they may also feed on the outer surface of 
the fruit, making it more or less unsalable. They also frequently enter 
greenhouses and attack cucurbits there. The larvae affect the vitality 
of the plant by attacking the underground stems and roots but are less 
injurious than the adults. 

The beetles are also injurious by carrying the "bacterial wilt" 
disease and "cucurbit mosaic" disease, not only from plant to plant, 
but also from one season to the next. As these diseases are serious ones, 



Fig. 107. — Adult 
Striped Cucumber Beetle 
{Diahrotica vittata Fab.) 
enlarged about six times 
(see hair line for true 
length). {From U. S. 
D. A. Farm. Bull. 1038.) 



THE COLEOPTERA 119 

often destroying plants, this adds to the importance of the insect as a 
pest. 

On the Pacific Coast is a slightly larger species known as the Western 
Striped Cucumber beetle (Diabrofica trivittala Mannerh.) which has much 
the same habits as the eastern form. In the more southerly portion of 
this region the adults are more or less active during the cold months. 
There appear to be at least two generations a year, and the methods given 
below for the control of the eastern species also apply for this one. 

Control. — This is a difficult insect to control, particularly where large 
areas are planted to any of the cucurbits and small garden methods will 
not pay. Protective methods, practicable in gardens, enable the plants 
to get well started, after which they are able to grow and produce the crop 
to quite an extent, despite the insect. Screening the plants before they 
come up, using fine-mesh wire or thin cheese-cloth stretched over a 
frame, works well for this purpose, provided the edge of the frame fits 
tightly into the earth everywhere, so that the beetles cannot burrow un- 
der it. Sometimes an excess of seed is planted with the idea of giving 
the insects enough food so that few or none of the plants will be too thickly 
infested to be able to live, and the poorest ones can be thinned out later. 
Gathering all but a few of the plants as soon as the crop has been har- 
vested, and burning them will leave the others for the beetles to gather 
on. These can then be sprayed with a strong stomach poison or a strong 
contact insecticide. Early cucurbits such as gourds, can be planted near 
later cucumbers and will act as trap plants, attracting the beetles. 

Spraying with a stomach poison, either alone or with Bordeaux 
mixture, is a good treatment if both sides of the leaves and the stems are 
well covered. Arsenate of lead 6 lb. of paste in 50 gal. of water seems 
generally to give the best results. The addition of 3 lb. of soap to each 50 
gal. of spray makes the latter adhere better to the plant. Arsenate of 
lime gives fair results. Dusting the plants with the dry poison mixed 
with air-slaked lime or plaster, at the rate of 1 lb. of the poison to any- 
where from 25 to 50 lb. of the inert material, sometimes works well. 
Its weakness as a treatment is mainly that it is difficult to get it onto the 
under side of the leaves and have it stay there. 

Whatever spray material is used, give the first treatment as soon as 
the plants show above ground and repeat two or three times at about 
weekly intervals, or oftener if rain makes it necessary. 

Several other minor remedies such as dusting the plants while the 
ground is moist, with tobacco dust, lime, or a mixture of the two; and 
hastening the growth and increasing the vigor of the plants by fertilizers 
and frequent cultivation, have some merit. If any or all the above-sug- 
gested treatments have been used, however, some of the insects will 
generally be present, none of these methods giving absolute freedom from 
the pest. 



120 



APPLIED ENTOMOLOGY 



The Corn-root Worms. — -There are several species of the genus Diabrotica 
which as larva^ appear to make a specialty of feeding either upon the base of the 
stem or the roots of corn. 

The Southern Corn-root worm or Twelve-spotted Cucumber beetle (Diabrot- 
ica duodecimpunctata Oliv.) is found practically everywhere in the United States 
east of the Rocky Mountains, but is usually a serious pest only from Maryland 
to Florida and as far west as southern Ohio, Indiana and Illinois, Alabama, 
Louisiana and Texas. The insect generally winters as the adult beetle (Fig. 108) 
under rubbish or in other protected places, except in the far South where it is 





Fig. 108. Fig. 109. 

Fig. 108. — Adult Southern Corn-root Worm (Diabrotica duodecimpunctata Oliv.), 
enlarged about eight times. {From U. S. D. A. Farm. Bull. 950.) 

Fig. 109. — Grub of Southern Corn-root Worm and its burrow in corn. Much en- 
larged. {From U. S. D. A. Farm. Bull. 950.) 

more or less active during this period. In spring it lays its eggs just below ground, 
on or near the young corn plants, and the tiny grubs which hatch, attack the corn, 
feeding on the roots and drilling into the stem just above them, boring out the 
crown and killing the bud (Fig. 109). From this habit the insect is often called 
the "budworm" or "drillworm." Small plants injured in this way break off 
at the crowns when pulled, and larger ones become dwarfed and yellowish. 
Other plants such as wheat, millet, alfalfa, etc., are also attacked by the larvae. 
The adult beetle is about a quarter of an inch long, yellowish-green with black 
head and legs and twelve black spots on its back. It feeds on squashes, cucum- 
bers and many other plants. There appear to be two generations each year in the 
North and three in the South, but most of the injury is caused by the first genera- 
tion. Burning over waste places where there is rubbish, during the cold months 
or on cold days will destroy many of the beetles which are seeking protection 



THE COLEOPTERA 



121 



there. A careful crop rotation, never planting corn twice in succession on the 
same land is also of value. Cotton, not being attacked by this pest is a safe crop 
to follow corn and a legume is desirable in the rotation. The insect is most 
serious in wet seasons and on low land. Corn is often more thickly planted on 
low places on this account, to increase the chance of getting a stand. Fertiliza- 
tion and cultivation increase the vigor and resistance of the plants to attack. 
In the far South corn planted during April is more likely to be injured than that 
planted before this time or after the tenth of May. 

The Western Corn-root worm (Diabrotica longicornis Say) occurs from 
Nova Scotia to the Gulf of Mexico and west to Minnesota, Nebaska and New 
Mexico, but is most injurious from Ohio 
to Tennessee and from South Dakota 
through Nebraska, Iowa and Missouri. 
The winter is spent in the egg in the 
ground and the grubs (Fig. 110) hatch 
in the spring and attack the corn roots 
(Fig. Ill) but never the stem. After 
feeding until full-grown they pupate in the ground and the adult beetles 
emerge in July and August and lay their eggs. There is therefore, but 
one generation a year. The adult beetles (Fig. 112) are about one-fifth 
of an inch long and, except for their black eyes, are entirely greenish or 
yeUo wish-green. They feed on the pollen and silk of corn and on the 




Fig. 110. — Grub of Western Corn-root 
worm {Diabrotica longicornis Say), much 
enlarged. {From U. S. D. A. Bull. 8.) 





Fig. 111. Fig. 112. 

Fig. 111. — Work of Western Corn-root worm in corn roots'. {From U. S. D. A. 
Bull. 8.) 

Fig. 112. — Adult Western Corn-root worm, enlarged. Hair line at right shows 
real length. {From U. S. D. A. Bull. 8.) 



blossoms and leaves of other plants, in August and September and if abundant 
then in a corn field, one may be certain that that field will be well stocked with 
eggs and therefore that corn should not be planted there again the following 
spring Corn attacked by the grubs at first produces shortened ears with kernels 
lacking at the tips: later it fails to produce the ears, and dwarfing of the plants 



122 



APPLIED ENTOMOLOGY 



occurs. Rotation of crops has proved a successful control for this insect in 
practically every case where it has been tried. 

Another species {Diabrotica vergifera Lee.) having similar habits and similarly 
controlled, is often destructively abundant in Colorado. 

On the Pacific Coast a different species, the Western Twelve-spotted Cucum- 
ber Beetle or Flower Beetle {Diabrotica soror Lee), appears to have the same gen- 
eral habits as its eastern relatives, but observations thus far indicate that the 
grubs are injurious mainly to alfalfa, beet, pea and peanut roots, while the adults 
do much damage to many plant leaves, buds and flowers. The winter appears 
to be spent in the adult stage and the eggs are laid from March to May in 
different latitudes. There are probably two generations each year. The adult 
is one-fifth to one-fourth of an inch long. The head, antennae, legs and body are 
black; the pronotum and elytra green or yellowish, the latter with twelve black 
spots often partly fused. Control thus far has been directed mainly against the 
beetles, spraying plants on which they are feeding with arsenate of lead (neutral) 
at the standard formula, using either water or Bordeaux mixture. 




•> 


< 


\ _ 


r 




¥ 


m 


^^ 




'\ 


. "IP 





a he 

Fig. 113. — Adult Flea Beetles: o, Spinach Flea Beetle, enlarged nearly five times; 
b, Potato Flea Beetle, enlarged about seven times; c, Egg-plant Flea Beetle, enlarged about 
seven times. (From U. S. D. A. Bulletins.) 

Flea Beetles. — Many tiny beetles belonging in the Chrysomelidae 
are known as Flea beetles because when disturbed they hop away like 
fleas. The economic forms vary in size from about a fifth to a fifteenth 
of an inch in length (Fig. 113). Most of them are blackish or steel- 
blue, though some have portions of the body yellow, whitish, red or 
other colors. The hind femora are very large, enabling the insects to make 
vigorous leaps. The adults feed on the leaves, eating tiny holes, while in 
most cases the larvae are root feeders, generally on the same plants which 
their adults attack, though in some cases they also attack the leaves. 
Many attack garden crops such as the potato, turnip, beet, spinach, 
rhubarb and radish, while other species feed on the strawberry, grape, 
tobacco, hop, clover, apple, Virginia creeper, willow, alder, etc. In most 
cases there are two generations a year, the first appearing early in the 
season and the second in mid-summer or early fall, though some species 
have but one generation and some have several. 

Control. — These insects which are often serious pests, appear to be 
repelled by Bordeaux mixture, but it is better to combine this with 



THE COLEOPTERA 123 

arsenate of lead, standard formula. Dusting with Paris green and land 
plaster may also be used with some success as a control method. Where 
the larvae mine in the leaves, as certain species do to some extent, treat- 
ment must be directed toward the destruction of the adults which indeed, 
should be the case with all the species. Where plants are started in seed 
beds and are attacked there, screening the beds with cheese-cloth is 
practicable. When plants from seed beds are set out they may be pro- 
tected by dipping them in 1 lb. of arsenate of lead paste in 10 gal. of 
water before setting them. 

It is believed that the Cucumber Flea-beetle like the Three-lined 
Cucumber Beetle may inoculate plants with the cucurbit wilt already 
referred to. Certainly the tiny holes made in the leaves by their feeding 
provide excellent places for the spores of fungi to establish themselves 
and produce disease. 

The Conimon Asparagus Beetle (Crioceris asparagi L.). — This insect 
reached this country from Europe about 1856 and is now present in the 
Eastern States as far south as North Carolina and westward to the Mis- 
sissippi River. Farther west it has been reported from several scattered 
localities, including California, and it may be assumed that it will in 
time become generally distributed. 




Fig. 114. — Common Asparagus beetle {Crioceris asparagi L.) : o, Adult; b, Egg; c, 
larva, just hatched; d, full-grown larva. Greatly enlarged: hair lines beside a and b show 
■ real length. {From U. S. D. A. Farm. Bull. 837.) 

The adult beetle (Fig. 114) is a little less than a quarter of an inch 
long. It is dark blue or bluish black, with a red thorax, and its elytra 
are dark blue and yellow, the former present as a band along the middle, 
Vv^ith two lateral extensions toward the sides into the yellow, while the 
outer border is reddish. The distribution and amount of the blue and 
yellow varies considerably according to the locality, the blue often so 
encroaching on the yellow as to leave only six spots of the latter color. 

The insect winters in the beetle stage in any protected place it can 
find, and as the asparagus plants begin to come up in spring, leaves its 
winter quarters to feed and lay its eggs (Fig. 115a). The beetles at this 



124 



APPLIED ENTOMOLOGY 



time feed on the stems and when abundant do considerable harm. The 
eggs are laid on the stems, singly, attached by one end, are dark brown 
in color, and hatch in from 3 to 8 days according to the temperature. 
The grubs (Fig. 114d), often called "slugs" are gray with black heads. 
They feed from 10 days to 2 weeks, gnawing the stems and thus aid the 
beetles in making these unfit for sale. Then they enter the ground and 
pupate for about a week which is followed by the emergence of the adults. 
The life cycle therefore is from about 4 weeks during hot weather to 6 or 

7 weeks in spring or fall. There are 
at least two generations in the North 
and probably three or four in the 
South each year. 

The later generations feed on 
the leafy growth and in the case of 
young plants may seriously weaken 
them. Eggs when abundant on the 
stems cut for market are objection- 
able, and a black fluid poured out by 
the grubs when disturbed, often stains 
the stems also. Fortunately, exces- 
sive heat appears to kill many of the 
grubs, and the alternation of severe 
cold with much warmer periods in 
winter, has a similar effect on hiber- 
nating adults. Several parasites and 
other enemies also reduce the numbers 
of this pest. 

Control. — Fresh air-slaked lime 
dusted over the plants while these 
are wet with dew is an excellent con- 
trol measure for small areas. Fowls 
feed freely on the insects and are therefore of value when allowed to run 
through the asparagus beds. For larger areas a frequent practice is to 
keep the plants as closely cut as possible, leaving a few stems here and 
there as traps on which the beetles can lay their eggs. These plants 
should be cut once a week and destroyed, others being then allowed to 
grow to take their places. Where cutting is not being done, spraying 
with arsenate of lead a little stronger than the standard formula is a 
very satisfactory treatment, the number of treatments required being 
generally not more than two or three at most during an entire summer. 

The Twelve-spotted Asparagus Beetle {Crioceris diwdecimpundata L.). — 
This insect arrived in this country from Europe about 1881 and was first dis- 
covered near Baltimore, Md. Though beginning its work here more than 20 
years later than the other species, it has already nearly everywhere overtaken the 
latter and is now widely distributed. 




Fig. 115. — Eggs, larvae and adults of 
Common Asparagus Beetle on the plant. 
Natural size. (From U. S. D. A. Farm. 
Bull. 837.) 



THE COLEOPTERA 



125 



The adult beetle (Fig. 116) is slightly larger and broader in proix)rtion to 
its length than the Common Asparagus Beetle. It is orange-red or brick-red 
above except for twelve black dots on the elytra. The life history and habits 
do not seem to differ much from those of the other species except in the follow- 
ing features. The beetle appears to depend upon flight rather than upon dodg- 
ing around the stems to escape its enemies: the egg is not attached by one 
end but by a side, to the plant; the larva feeds inside the berries and is orange 
to yellowish in color. The hibernating insects feed on the young plants like the 
other species but the beetles of later generations feed on the berries. Control is 

similar to that for the Common Asparagus Beetle 

except that dusting with air-slaked lime will not 

reach the larva?. 

The Grape-root Worm {Fidia vilicida Walsh). 

■ — The Grape-root Worm appears to be a native 





Fig. 116. Fig. 117. 

Fig. 116. — Adult Twelve-spotted Asparagus Beetle (Crioceris duodecimpunctata 
L.) nearly six times natural size. {From U. S. D. A. Farm. Bull. 837.) 

Fig. 117. — Adult Grape-root Worm (Fidia viticida Walsh), about natural size, and 
its work on a grape leaf. {Modified from. Cornell Exp. Sia. Bull. 208.) 



of this country and is found from New York to North Carolina (and 
Florida?) and west to Dakota, Missouri and Texas. There is also a California 
record for it but it appears to be largely replaced there, by the California 
Grape-root worm {Bromius obscurus L.). The insect passes the winter as 
the nearly- or full-grown larva, a number of inches deep in the ground, but in 
spring it comes nearer the surface and feeds on the roots of the grape until full 
grown. Pupation usually occurs two or three inches below the surface and the 
adult beetles begin to emerge about the time blossoming of the grape ends, most 
of them appearing during a period of 4 or 5 weeks. The beetles (Fig. 117) are 
brown, covered with whitish hairs; are rather stout, about a quarter of an inch 
long and have long legs. They feed on the grape leaves, making irregular holes, 
often so connected as to form narrow, crooked slits. The eggs are laid, several 
hundred in all, placed in clusters of about 30 or 40, mainly under loose strips 
of bark. These hatch in about 10 days and the tiny grubs drop to the ground 
and work down to the roots consuming the smaller ones entirely and burrowing 
in the larger ones, until winter, when they are full grown or nearly so. 

When these insects are abundant the grape vines may be killed in a year or 
two but the usual result of their presence is to so check the growth of the plants 
that little or no crop is obtained. The grape-raising territory of western New 
York, Pennsylvania and Ohio appears to suffer most from the attacks of this pest. 



126 APPLIED ENTOMOLOGY 

Control. — The adult beetles can be killed by spraying the leaves with arsenate 
of lead using 3 or 4 lb. of the paste in 50 gal. of Bordeaux mixture, just before 
or as soon as the first signs of feeding appear, and again after 10 days. Great 
care must be taken, however, to do this work thoroughly, as the beetles avoid 
sprayed foliage. The beetles may also be jarred off the vines, particularly on 
warm days, onto sticky boards, fly paper, or sheets or some other type of catcher 
placed beneath the plants, whence they can be gathered and destroyed. The 
pupse are located within a few inches of the top of the ground and are mostly 
within two or thre(^ feet of the vine. In this state of their existence they are easily 
destroyed by any thorough breaking up of the soil where they are, and this is 
taken advantage of by throwing up the earth on each side of the vines in the fall 
to form a ridge. Most of the larvae work up into this to pupate, the following 
spring, and while the insects are in the pupa stage there this ridge should be hoed 
away by a horse-hoe and by hand, or by the latter alone for small areas. Later 
cultivation will reach some of those escaping the first treatment which in the 
grape belt named is usually about the middle of June. 

The Calif ornian species is a little smaller than the one just described, and jet- 
black or brown. Its habits and methods for controlling it are about the same as 
with the eastern pest. 

The Elm Leaf Beetle {Galerucella luteola Muls.). — This European insect 
appears to have reached this country at Baltimore about 1834 and has now spread 
through most of the New England and Middle Atlantic States and westward 
nearly to the Mississippi River, though not everywhere present within these 
limits. 

The adult beetle (Fig. 118) is about a quarter of an inch long, dull yellow in 
color, with black spots on the head and pronotum, a black band near the outside 
of each elytron, and a short streak at the base of each, nearer the middle. The 
beetles winter over in protected places and in the spring the dull yellow has 
changed to an olive-green (Fig. 118). They fly to the elm trees when the foliage 
develops, and feed, eating irregular holes in the leaves and from time to time lay- 
ing yellow eggs on the underside of the leaves, usually about 25 in number and 
nearly always in two rows, side by side (Fig. 118). The eggs hatch after about a 
week and the tiny yellow and black grubs feed for about 3 weeks, working on the 
under surface and leaving the upper epidermis of the leaf unbroken. When full- 
grown (Fig. 118) and about half an inch long they crawl down the tree to the 
trunk and pupate for from 1 to over 3 weeks according to the temperature, either in 
crevices of the bark on the lower part of the trunk or on the ground near the foot 
of the tree (Fig. 118). In the more northerly states the larvae feed during June. 
Farther south they begin in May and a second generation feeds during the late 
summer or early fall. The European elms are most severely injured by this 
insect but other species often suffer greatly. 

Control. — Spraying the trees about the time the eggs are laid, i.e., soon after 
the leaves are fully grown, with arsenate of lead is the usual method of control. 
The strength of the material should be increased above the standard to 5 lb. of the 
paste, to obtain good results, and it should be kept in mind that as the grubs do 
not feed on nor reach the upper surface of the leaves, the spray shoald be directed 
as far as possible onto the under surfaces. 



THE COLEOPTERA 



127 




L. M. Joutei. 1900 



Fig. 1 IS. — The Elm Leaf Beetle (Galerucella hiteola Muls.) : 1, egg cluster; la, single egg 
greatly enlarged; 2, recently hatched larva (grub); 3, full-grown larva; 4, pupa; 5, 
beetles after wintering over; 6, freshly emerged beetles; 7, under surface of leaf showing 
grubs, their work and a few holes eaten by adult beetles; 8, leaf nearly skeletonized by the 
larvae; 9, leaf eaten by adults. Hair lines by Figs. 1 to 6 show natural size: 7, 8 and 9 
natural size. {From Bull. 332 Ohio Agr. Exp. Sta. After Felt.) 



128 



APPLIED ENTOMOLOGY 




Fig. 119.— Tortoise 
Beetle (Deloyala clavata 
Fab.) about 2j-^ times 
natural size. (Original.) 



Destroying the descending larvse and the pupae on the lower part of the trunk 
and on the ground, with a strong kerosene emulsion spray is an auxiliary treat- 
ment, but as these individuals have completed their feeding, this affects only the 
abundance of the next generation. Power sprayers are a necessity for spraying 
tall trees in the way here described. 

The Tortoise Beetles are interesting members of the Chrysomelidse 
(Fig. 119) because of their resemblance in form to tortoises and inmost 
cases, on account of their golden color, which is 
lost after death. Some species attack the sweet 
potato but are not usually serious pests. They are 
small insects, usually not over a quarter of an inch 
long, nearly as wide, and often with black mark- 
ings. If they become injuriously abundant, spray- 
ing the leaves on which the larvae feed, with arsenate 
of lead will control them. 

Family Bruchidae (Pea and Bean Weevils). — In 
this group of small beetles the head is extended 
downward into a broad but short snout. The 
elytra are shorter than the body leaving the hinder 
end of the abdomen exposed above. The larvae feed in the seeds of 
leguminous plants such as peas and beans, and frequently cause a great 
amount of damage. Several kinds are abundant in the United States, 
the pea weevil and the common bean weevil being perhaps the most 
important. 

The Pea Weevil (Bruchus pisorum L.). — This pest of field and garden 
peas winters as the adult beetle (Fig. 120a) either in peas or in protected 
places, and after the pea pods 
begin to form, lays its eggs on 
them. It is about one-fifth of 
an inch long, brownish, with 
black and white spots. The 
larvae (Fig. 1206) bore their way 
into the peas, the holes they 
make either closing up or being 
too small to be noticed, and feed 
on the contents of the pea until 
full-grown. They then pupate 
(Fig. 120c) and upon the pro- 
duction of the adult, those in the South leave the peas, while in the 
North they remain. in them over winter. Only one weevil usually feeds 
in a pea and the insect cannot reproduce in dried peas. There is there- 
fore only one generation a year except where spring and fall crops of peas 
are grown. 




Fig. 120. — Pea Weevil (Bruchus pisorum L.) : 
a, adult beetle; h, larva (grub); c, pupa. 
Greatly enlarged. {From U. S. D. A. Farm. 
Bull. 983.) 



THE COLEOPTERA 



129 



The Common Bean Weevil {Bruchus obtedus Say). — This insect is 
now found in nearly all parts of the world. The beetle is smaller than 
the Pea Weevil and is brownish-gray in color, its elytra slightly mottled 
(Fig. ] 21). The beetle lays its eggs on or in the pods of the beans growing 
in the field, either in holes made, or in cracks caused by the pods splitting. 
In the case of shelled beans the eggs are placed on the beans themselves. 
The larvae gnaw their way to and into the beans, and unlike the Pea Weevil, 
a number may enter the same seed and feed upon its substance. Devel- 
opment from the egg to the adult occurs within the bean and the adult 
finally escapes through a circular hole it has cut in the skin after having 
spent from 3 weeks to nearly 3 months there, according to the tempera- 
ture where the beans are kept. When infested 
l)eans gathered in the field are brought in, their 
infestation may not be apparent, but after 
being kept a while, the adult beetles will escape 





Fig. 121. Fig. 122. 

Fig. 121. — Adult Common Bean Weevil {Bruchns obtectus Say), greatly enlarged: 
hair line at right shows real length. (From U. S. D. A. Farm. Bull. 983.) 
Fig. 122. — Work of Bean Weevils, natural size. {Original.) 

and lay their eggs for another generation which will develop in the same 
seeds if these are kept where it is fairly warm (Fig. 122), and thus by 
spring there may be practically no beans left to plant. Six generations 
may be produced in a year in the South and if the beans are kept where 
it is warm during the colder months, as many may occur in northern 
localities, though in the field it is doubtful if there are more than one 
or two. 

Another species, the Cowpea Weevil {Bruchus chinensis L.) which feeds 
on the cowpea, and other peas, and beans, is more abundant in the South, and a 
fourth, the Four-spotted Bean or Cowpea Weevil {Bruchus quadrimaculatus Fab.) 
has a wide distribution, probably wherever cowpeas are grown. Both of these 
species breed generation after generation in stored cowpeas, and in warm 
temperatures there may be a number of generations each year. 

The Broad Bean Weevil {Bruchus rufimanus Boh.) in its life and habits more 
nearly resembles the Pea Weevil than the other species above considered. It is 
injurious in Europe and Northern Africa and has now established itself in Cali- 
fornia. The beetles resemble the Pea Weevil but seem to prefer broad beans or 
horse beans. They appear in the fields in March and lay numbers of eggs on the 
iaean pods and the grubs on hatching make their way to the young beans, several 



130 APPLIED ENTOMOLOGY 

often entering one bean. Feeding is completed by early August and the adults 
are produced later in the fall. They generally winter in the beans but do not 
breed in dried beans, there being therefore only one generation a year. 

Injuries. — The damage caused by the attacks of pea and bean weevils 
is of two kinds: injury by consuming the bulk of the seed and leaving the 
remainder unfit for food; and injury by so reducing the stored material 
or the germ itself that the seed cannot germinate and grow. 

Control of Pea and Bean Weevils. — The original attacks of these in- 
sects are upon growing plants out-of-doors. Here no control seems pos- 
sible. When the crop is gathered, however, treatment can easily be 
given by shelling at once, placing the seed in gas-tight receptacles, and 
fumigating it with carbon disulfid, using this at the rate of at least 8 or 
10 lb. for every 1,000 cu. ft. of space in the container, and continuing the 
treatment for at least 1 — better 2 — days. The disulfid may be poured di- 
rectly onto the top of the seeds. For best results this should be done in a 
place where the temperature is at least 75°F. Then the seed should be 
packed in weevil-tight boxes, but it would be wise to examine it again 
after a time and if living weevils are still present, give it another treat- 
ment. Where the seed is not to be used for food, packing it in air-slaked 
lime at the rate of 1 part by weight of lime to 2 or 3 parts by weight of 
seed has proved satisfactory. Even where use as food is intended, this 
method can be used if the seed is thoroughly washed before cooking. 
Cold storage below 34°F. will prevent development of the Insects. Heat 
will destroy the weevils and if seed is raised to 131°F. and kept at that 
temperature for an hour, this will kill all the weevils present. Appar- 
ently, treatment in this way and for this length of time will not prevent 
germination. None of these methods will prevent reinfestation if the 
seeds are afterwards exposed to attack by insects from outside, where 
the temperature is such that they are active. In general then, give the 
first treatment immediately after gathering, and store in tight containers 
and preferably in a cold place. 

The shorter seasons and cold winters of the North give the pea and 
bean weevils less opportunity to increase through a number of generations 
than in the South, and many of the adults are killed by the cold. North- 
ern climates for these reasons are therefore better for the extensive pro- 
duction of seeds of these plants. 

Family Cerambycidae (Round-headed Borers or Longicorn Beetles). — 
The insects of this family are for the most part of fair size, a number being 
several inches in length. Their antennae are usually long — sometimes 
longer than the body — and the beetles are frequently bright-colored and 
strikingly marked (Fig. 123). 

The larvae are chiefly wood-borers, living in burrows in the trunks or 
roots of trees, or the pith of plant stems, and are termed round-headed 



THE COLEOPTERA 131 

borers because the thoracic segments are circular in outline and the 
tunnels they produce are therefore also of this shape. The larvae them- 
selves are soft, whitish or yellowish grubs, withstrong jaws, and most of 
them have no legs. The eggs are usually laid on the bark of the tree and 
the larvae live on the wood they tunnel out, for a varying period, usually 
2 or 3 years, and pupate in the tunnels just beneath the bark, 
through which the emerging beetle finally gnaws its way and escapes. 




Fig. 123. — Cerambycid {M onohammus) , natural size, showing long antennae. {Original.) 

Some species cut the stem in which they live, nearly through, and when 
it breaks off, fall with it to the ground, thus pruning the tree. Those 
which tunnel in the heart-wood of timber trees often greatly reduce the 
value of the timber by their holes. Some species attack sound wood and 
apparently vigorous trees, while others seem to prefer trees already un- 
healthy, for their food. The family is a large one and contains many 
forms injurious to shade and forest trees. 

The Round-headed Apple-tree Borer (Saperda Candida Fab.). — This 
serious enemj^ of the apple tree is found practically everywhere in the 
eastern United States except in the extreme South, and westward into 
Minnesota, Iowa, New Mexico and Texas. It also attacks the service 
tree, pear, quince, thorns, mountain ash, and a few other Rosaceae. The 
adult beetle (Fig. 124) is a little less than an inch long, pale brown above, 
with a pair of white stripes extending backward from the head across 
the pronotum and along the elytra to their tips at the hinder end of the 
body. Beneath, it is silvery white. It appears during the late spring 
and summer months and lays its eggs singly here and there in small slits 
it cuts in the bark near the base of the tree, laying about 15 to 30 in all. 
On hatching, 2 to 3 weeks later, the larva burrows through the bark to 
the sap-wood, and there makes broad, rather shallow galleries just under 
the bark and in general working downward. The bark over these gal- 
leries frequently dries and cracks, or the borer makes holes in it, letting 



132 



APPLIED ENTOMOLOGY 



out the borings and castings, often called "sawdust" which shows the 
location of the burrows. After hibernating during the winter the borer 
(Fig. 124) resumes its work the following spring, still feeding on the sap- 
wood, and if the tree is small or if several borers are present, girdling may 
result. After a second winter in hibernation the borer turns its atten- 
tion to the heart-wood, boring into this, and finally as it approaches full 
growth, working its way out toward the surface, being now about three- 
quarters of an inch long. After a third winter of rest the larva pupates 
in its tunnel in the spring, having previously carried the tunnel out to the 
bark, and the adult beetle emerges after about 3 weeks. One generation 




Fig. 124. — Round-headed Apple-tree Borer (Saperda Candida Fab.) : back and side 
views of adult beetle on bark and exit hole; full-grown larvee (borers). {After Rumsey 
and Brooks.) 



accordingly requires 3 years in which to complete its life history but 
this comes in parts of 4 calendar years. In the southern part of its 
range this is shortened to 2 years and in intermediate regions some may 
require 2, and some 3 years. 

Small trees suffer most severely by the attacks of this pest, a single 
borer often entirely girdling a tree: larger ones are weakened and become 
unhealthy and if strongly infested may also be killed. 

Control. — Various methods of control have some value. "Worming" 
the trees, i.e., cutting out the young borers early in the fall is a good 
practice if it is thoroughly done and if the cutting is carried on carefully. 
Litter should be carefully scraped away from the trunk to expose any 
sawdust present, and from this the burrows can be located and the dead 
bark cut out and the borer killed, either in place under the bark or by 
running a flexible wire into its burrow if it has gone deeper into the tree. 
In cases where the borer cannot be reached by the wire, a little carbon 



THE COLEOPTERA 133 

disulfid on cotton placed in the burrow, the opening then being closed 
with mud, will serve the same purpose. Worming should be done in 
early fall; the work should be thorough, and host trees of every kind 
within several hundred feet of the orchard should be worked at the 
same time for the beetles do not usually fly far and if the immediate 
neighborhood is cleared of them, reinfestation from a distance does not 
occur very frequently. 

Thick paints are sometimes used as repellents. These are applied 
beginning a few inches below ground, the earth being removed for the 
purpose, and extending about a foot up the trunk, just before the egg- 
laying period begins. The paint should be thick and be thoroughly 
applied and should be pure white lead in raw linseed oil, as other materials 
have been known to injure the trees. 

Protectors, such as newspaper wrappings (several layers thick), 
building paper, cloth, wire netting, etc., may be used, being placed around 
the trunks before egg-laying begins. In all cases, however, these must 
enter the ground at the bottom and be tightly fitted around the trunk 
at the top and be without holes or cracks through which the beetle can 
crawl. Asphaltum has given fair results in some cases, but appears to 
be liable to injure the tree. 

As the beetle feeds somewhat on twigs and leaves, the usual sprayings 
with a stomach poison for other apple pests are liable to kill some of the 
beetles also. Woodpeckers feed freely on the borers. 

Family Coccinellidae (Lady Beetles, Lady Bugs or Lady Birds). — 
The lady beetles are nearly all carnivorous, feeding both as larvae and 
adults on scale insects, plant lice and other important pests. They are 
generally small beetles, nearly circular or oval in outline, strongly convex, 
often resembling in size and form a split pea. Their colors are usually 
black and red or reddish-yellow, sometimes the spots or markings being 
black on a red ground, sometimes the reverse. In a number of species 
the beetle is entirely black (Figs. 125 and 126). 

The larvae (Fig. 126) are active and crawl around over leaves, twigs, 
etc., searching for their food. They are dark colored, but frequently 
have a few spots of yellow or blue on the side of the body, and their 
general appearance has suggested to some persons, a resemblance to 
alligators. 

The family is quite a large one, and its species are abundant and well 
distributed over this country. Among the more useful or noticeable of 
the family is the Two-spotted Lady beetle {Adalia bipunctata L.), one of 
the smaller species averaging about a sixth of an inch in length (Fig. 1256). 
The head is black, sometimes with two yellow spots; the pronotum black 
with yellow side margins, and the elytra are red with a black dot in the 
center of each. This insect frequently winters in houses and may be found 
on the windows in spring trying to escape. It is often mistaken for some 



134 



APPLIED ENTOMOLOGY 



injurious household pest on this account. This species feeds mainly on 
plant lice, but to some extent also on the pear psylla. Another species of 
about the same size is known as the Twice-stabbed Lady beetle (Chilo- 
corus bivulnerus Muls.). Here the head and pronotum are black, as are 
also the elytra, except for a red spot in the center of each, thus just 
reversing the elytral color pattern of the last described species. It feeds 
on scale insects and also on plant lice and the Colorado Potato Beetle. 







Fig. 125.— Examples of Lady Beetles: a, Twice-stabbed Lady Beetle (Chilocorus 
bivulnerus Muls.) : b. Two-spotted Lady Beetle {Adalia bipunclata L.) ; c, Nine-spotted 
LadyBeetle (Coccinella novem,notata Hbst.) : d, Spotted Lady Beetle {Coleomegilla fuscilabris 
Muls.): all about twice natural size. {From Conn. Agr. Exp. Sta. Bull. 181.) 

Other common species are the Nine-spotted Lady beetle {Coccinella 9-notata 
Herbst.) with nine black spots on its red elytra; the Fifteen-spotted Lady beetle 
(Anatis 15-punctata Oliv.), the largest species in the Northeastern States, which 
has 15 black spots on its red elytra; the Pitiful Lady beetle {Pentilia misella Lee), 
a very tiny black species which feeds on scale insects and aphids, and the Spotted 
Ijady beetle (Coleomegilla fuscilabris Muls.) about a fifth of an inch long, usually 
bright pink with black spots and with its body rather oval in outline, somewhat 
pointed behind. This species feeds on many kinds of plant lice and other small 
insects and tends to hibernate in clusters, often several hundred together, under 
leaves at the bases of treetrunks. 




Fig. 126.- 
d, eggs. 



-Different stages of the Nine-spotted Lady Beetle: a, adult; b, larva; c, pupa; 
All much enlarged. (Modified from Palmer, Ann. Ent. Soc. Am., vii, 1914.) 



The Convergent Lady beetle {Hippodamia convergens Guer.) is about 
a quarter of an inch long, with two converging yellow marks on the 
pronotum and six black spots on each elytron. This widely distributed 
species has been found feeding on a number of kinds of plant lice and in 
addition, on asparagus beetle larvse, eggs of the Colorado Potato beetle 
and of the Grape-root worm, red spiders, the Bean Thrips, Alfalfa Weevil 
and Chinch Bug. On the Pacific Coast it gathers in enormous numbers 



THE COLEOPTERA 135 

in the high mountains to hibernate and while thus collected in quantities 
they are gathered and in spring distiibuted through the truck-growing 
regions to attack the plant lice, about 30,000 being regarded as enough to 
protect the plants growing on 10 acres. Several tons are often collected 
for distribution for this purpose. It takes nearly 1,500 of these beetles 
to weigh an ounce. 

Because of their efficiency as feeders on insect pests, a number of kinds 
have been introduced into this country to attack the special insects of 
their native lands which have reached the United States and have become 
pests here. Among these are the Vedalia {Novius cardinalis Muls.) 
(See Fig. 216), imported from Australia to attack the Cottony-cushion or 
Fluted Scale; the Mealy-bug Destroyer {Cryptolcemus montrouzieri Muls.), 
brought also from Australia to attack several kinds of Mealy-bugs found 
in California; the Steel-blue Lady beetle (Orcus chalybeus Boisd.) which 
feeds on a number of kinds of Armored Scales; and the Black Lady beetle 
{Rhizobius ventralis Erichs.) which is an active enemy of the Black Scale 
{Saissetia olece Bern.); besides numerous other species. Many of these 
imported forms have done valiant work in their attacks upon their 
ancient foes in the country to which both have come, but in some cases 
this attempt to aid nature in the control of insect pests has been less 
successful, and it is evident that the success of each experiment of this 
kind can rarely be determined beforehand. (See Cottony Cushion Scale, 
Chapter XXVI). 

Family Tenebrionidae (Darkling Beetles). — This rather large family of beetles 
contains many forms found on the ground and superficially resembling the Cara- 
bidse. They are usually rather slow of movement, however, feed on vegetable 
instead of animal food, and while their fore and middle 
tarsi are each composed of five segments as in the Carabids, 
their hind tarsi each have only four. They are particularly 
abundant in the Southwest and West, though a number 
are present practically everywhere. 

The Yellow Meal -Worm {Tenebrio molitor L.) about 
three-quarters of an inch long (Fig. 127), is often found 
around stores of grain, in pantries, stables etc., and its larva 
which closely resembles a wireworm, feeds upon meal and 
similar materials. It is often raised as food for cage birds. 
Where abundant, a thorough cleaning out of infested places, t,J^?' ^~''7m^^^]°^ 

. • 1 1 1 1- r- . . Meal-worm {Tenebrio 

followed by sprinkhng air-slaked hme around, or fumigation molitor L.), about 

of the infested material with Carbon disulfid, is all that is natural size. {Orig- 
inal.) 
necessary. 

Family Meloidae (Blister Beetles). — The insects of this family also 
have but four segments to each hind tarsus. The body is quite cylin- 
drical and rather soft, and the head joins the thorax by a distinct neck 
(Fig. 128). Many of the members of this family contain a substance 




136 



APPLIED ENTOMOLOGY 



called cantharidin, which when applied to the skin, produces blisters. 
The bodies of these species, powdered, are used in medicine under the 
name " cantharides " or "Spanish flies," for blistering purposes. 

A dozen or twenty kinds of Blister beetles, averaging from half 
an inch to over an inch in length are more or less serious pests as adults, 
feeding during the summer or fall on foliage and blossoms, various vege- 




FiG. 128. — Adult Rlister Beetles: a, Black Blister Beetle {Epicaufa pennsylvanica 
jDe G.) ; b. Ash-gray Blister Beetle (Macrobasis unicolor Kby.) ; c, Striped Blister Beetle 
(Epicauta vittala Fab.); all about natural size. {Modified from U. S. D. A. Bulletins.) 

tables and ornamental plants being attacked. Vegetable crops are 
sometimes seriously affected. The larvae on the other hand, feed on the 
eggs of various species of grasshoppers and are therefore beneficial. 
The adults are not easily controlled as they are rather resistant to arseni- 
cal poisons, and as they fly freely, it is difficult to reach them with contact 
insecticides. In cases where stomach poisons can be applied, arsenate 

of lead, taking about 4 lb. (if the 
paste be used) to 50 gal. of water, 
has proved the best treatment. 
Where this cannot be done, hand- 
picking, and screening valuable 
plants with netting, may be 
resorted to. 

RHYNCHOPHORA (Snout Beetles) 
The snout beetles are included 
in several families. Some are 
called curculios, weevils, and bill- 
bugs, and those of one family, the 
larvae of which work in the bark 
and wood of trees, are called Engraver beetles and also bark borers. 
Over twenty-five thousand species of Rhynchophora are known (Fig. 129). 
Except for this last named family, most snout beetles feed on fruits, 
nuts, etc., though a few attack stems and leaves. The white, nearly 
always footless larvae, also feed for the most part on such materials, and 
a number are very destructive and therefore important pests. 




Fig. 129. — Examples of adult Snout 
Beetles showing differences in the develop- 
ment of the snout. About twice natural 
size. {Original.) 



THE COLEOPTERA 



137 



The Plum Curculio (Conotrachelus nenuphar Herbst). — This Insect 
is a native of the United States and formerly fed upon the wild plum and 
thorn fruits, but now also attacks cultivated plums, prunes, cherries, 
nectarines, apricots, apples and peaches. It is found practically every- 
where east of the Rocky Mountains, though in 
the western portion of this area it seems to be of 
less importance than elsewhere. The adult beetle 
(Figs. 130 and 131) is small, being only about a 





Fig. 130. Fig. 131. 

Fig. 130. — Adult Plum Curculio {Conotrachelus nenuphar Hbst.), view from above. 
About five times natural size. {Modified from U. S. D. A. Bur. Ent. Bull. 103.) 

Fig. 131. — Side view of adult Plum Curculio showing humps on the back. Enlarged 
about five times. {Modified from U. S. D. A. Bur. Ent. Bull. 103.) 

fifth of an inch long, dark colored as a whole but mottled with gray 
and brown. Its elytra are rough and on each is a black, shining hump 
a little behind the middle. 

This pest spends the winter, or the colder months in the South, hiding 
in any protected place it can find, particularly in the woods, in stone 
walls or under leaves. It appears 
about the time the plum buds open in 
spring and feeds more or less on the 
developing leaves. When the fruit 
begins to develop, the beetles turn 
their attention to it, feeding by cutting 
a circular hole through the skin and 
consuming the flesh beneath to a 
depth about equal to the length of 
the snout of the insect. They also 
begin now to lay their eggs in the 
young plums, cutting a hole in the 
skin and then running the snout ob- 
liquely into the flesh beneath. In 
this cavity the egg is placed and it is 
then pushed farther in by the snout. 
The beetle next cuts a crescent-shaped 
slit through the skin close to the 
egg (Fig. 132) and carries this down through the flesh beneath the egg 
which thus comes to lie in a sort of flap which wilts and remains soft, and 
the crushing of the egg by the growth of firm tissue there is prevented. 




Fig. 132. — Egg puncture and feeding 
puncture of Plum Curculio in young 
plums. {From U. S. D. A. Farm. Bull. 
908.) 



138 



APPLIED ENTOMOLOGY 



Several hundred eggs are laid in this way and the "spot and crescent" 
marks of the insect on small plums are familiar to plum growers. The 
fruit often pours out gum at these places, probably in an attempt to 
repair the injury. 

The eggs hatch in a week or less and the tiny whitish grub bores 
through the flesh, and in stone fruits passes to the stone, around which it 
feeds for about two weeks or until full-grown. It then leaves the fruit, 
and as this in most cases has fallen before this time because of the injury, 
the larva finds itself on escaping, on the ground. Into this it now burrows 
an inch or two and pupates. About a month later the adult beetle 
emerges, comes to the surface of the ground and attacks fruit for food, egg- 
laying rarely if ever taking place at this season, and when cold weather 
comes on it locates in some protected place for the winter. There is 
accordingly, but one generation a season. 




Fig. 133. — Apple showing injury by Plum Curculio in fall. 

Sta. Bull. 98.) 



{Modified from III. Agr. Exp. 



This insect, both by its feeding and egg-laying punctures, affects 
the value of the fruit not entirely destroyed, not only in appearance but 
by the opportunity these cuts afford for the entrance of the spores of 
disease-producing fungi, and the destruction in the United States which 
it causes has been estimated at over eight million dollars annually. 
While the insect rarely succeeds in developing in the apple, the punctures 
cause dropping of the fruit or its malformation, and the production of 
hard, woody places in the pulp. In the fall its feeding holes in apples 
also cause much injury (Fig. 133). 

Control. — No one method nor even all the methods of control taken 
together will give entire freedom from this pest. A combination of 



THE COLEOPTERA 139 

treatments, however, will accomplish considerable in this line. The 
usual measures taken are as follows: 

(1) Remove all opportunities for the successful wintering of the 
adults, as far as possible. Rubbish, stone walls, and trash of all sorts 
should be removed. Plum orchards near woodland are poorly located 
from this standpoint. (2) The curculio prefers shade in which to work, 
and larvae even inside fallen fruit are unable to survive any long exposure 
to direct sunlight. The trees therefore should be so pruned as to let the 
sunlight through all parts, and fallen fruit should be exposed to the sun 
by proper treatment of the ground under the tree. (3) Fowls and hogs 
will eat many of the larvae in the fallen fruit and larvifi or pupae in the 
ground, and should be allowed to run under the trees; or thorough, shallow 
cultivation under the trees should be given from the time the larvae begin to 
leave the fruit until at least 6 weeks later, to destroy the insects there. 

(4) Spraying with arsenate of lead either alone or combined with the 
self-boiled lime-sulfur has been fairly successful if the applications be 
thorough and at the right times. For plums spraying with 23^^ lb. of 
lead arsenate paste (13^^ lb. of the powder) in 50 gal. of water or lime- 
sulfur as soon after the blossoms fall as leaves begin to develop, and the 
treatment repeated 8 or 10 days later has proved the best method. 
Cherries can be treated in the same way. With peaches, 2 lb. of the 
arsenate in 50 gal. of water, to which the milk of lime obtained by slaking 
2 lb. of quick lime has been added, is sprayed as soon as the "shucks" 
are beginning to shed from the blossoms. About 3 weeks later a spray 
of 2 lb. of the arsenate in 50 gal. of the self-boiled lime-sulfur is made. A 
third treatment about a month before the fruit begins to ripen, using the 
lime-sulfur only, is also often given. For apples the precautions neces- 
sary in spraying stone fruits with arsenate of lead need not be taken. 
Here the treatments commonly given for the Codling Moth (see Chapter 
XXIX) are also effective at those times for the Curculio, though later 
similar applications may also be necessary if the insects are abundant. 

(5) Where only a few stone-fruit trees are involved, jarring them early 
in the morning, after spreading white cloth under them, is a good treat- 
ment. The beetles at that time of day are sluggish and drop onto the 
cloth when the tree is given a sudden blow, and they can then be gathered 
and destroyed. This should be begun as soon as the blossoms have all 
fallen and continued until the beetles no longer appear. 

The Plum Gouger (Coccotorus scutellaris Lee.)- — This plum pest like the last, 
is a native of this country and is found from New York west to the Rocky Moun- 
tains and south to Texas. It appears to be destructive, however, mainly west of 
the Mississippi River. The adult (Fig. 134) is somewhat larger than the Plum 
CurcuUo. The head and thorax are dull yellow and the elytra are lead-gray in 
color, and the surface is without any humps or other irregularities. In many 
regards the habits of the Gouger are like those of the Plum Curculio, but it leaves 



140 



APPLIED ENTOMOLOGY 



its winter quarters earlier than the last named insect and feeds for a time on the 
opening buds and leaves, gouging holes in the blossoms (Fig. 1346) and thus caus- 
ing them to drop off. Feeding holes and egg punctures in the young plums 
(Fig. 134c) are holes into the flesh in some of which the eggs are placed, but many- 
more holes are made than eggs deposited. The grubs work their way to and into 
the stone or pit and feed on the flesh (seed) within until full grown. Each then 
gnaws a hole through the stone, after which it pupates inside the stone, the adult 
appearing in late August and September. There appears to be but one insect in 
a fruit. 




a b c 

Fig. 134. — Plum Gouger {Coccotorus scutellaris liec.) : a, adult beetle about three 
times natural size; h, plum blossoms attacked at their bases by the beetle; c, young plums 
punctured by the beetle. {Modified from Minn. Agr. Exp. Sta. Bull. 66.) 

Plums attacked by the Plum Gouger do not drop, but mature on the tree, but 
such plums are worthless for market because of the injured spots and because of 
the deformed fruit produced. 

Control. — Picking off the injured plums before the beetles emerge in the fall 
has been recommended as a method of control for this insect, and jarring in spring 
has also been advised; though the beetles do not drop as freely as in the case of the 
Plum Curculio. It is possible that spraying with arsenate of lead as for the 
Curculio, making the first application as soon as the buds are open enough to 
provide any surface for the poison to adhere to, may prove of some value. 

The Cotton Boll Weevil {Anthonomus grandis Boh.). — This is at the 
present time the most serious insect pest of cotton which we have. 
Recent estimates place the destruction by the boll weevil at about 400,000 
bales per year, which at average prices for the cotton not thus destroyed 
would be many millions of dollars. Diversification of crops has come 
into practice, however, where the cotton crop has suffered, so that in a 
number of the affected States the total value of all crops after the appear- 
ance of the weevil, has been greater than before. In some cases then, 
the loss to cotton has been more than made up by turning to other crops, 
but the reduction in the amount of cotton needed for use in the world is 
important. 

The cotton boll weevil is a native of tropical America, whence it 
spread northward through Mexico, and about 1892 entered Texas. Since 
that time it has extended its area of infestation, reaching the Atlantic 



THE COLEOPTERA 



141 



Coast in Georgia in 1916 and in time it will probably be present every where 
in the cotton belt, except perhaps in the more arid portions and in places 
where it can find little protection during cold weather. 

The adult boll weevil (Fig. 135) varies considerably in size but aver- 
ages about a quarter of an inch in length. When it first emerges from 
the pupa it is light brown, but it soon becomes gray or almost black. 
It winters as the adult, hiding under rubbish, in cracks in the ground, in 
Spanish moss growing on the trees, or in fact in any protected place, 
though those which winter in the cotton fields appear to be least protected 
and hence least liable to survive, while those in wooded areas winter more 
successfully. 




a he 

Fig. 135. — Cotton Boll Weevil {Anthonomus grandis Boh.) ; a, side view of adult 
beetle enlarged about six times; b. larva (grub); c, pupa; both much enlarged. {From 
Sanderson: Insects Injurious to Farm, Garden and Orchard.) 

In spring the beetles leave their winter quarters, the time generally 
varying from March to the last of June. "In the spring and throughout 
the fruiting season of cotton the eggs are deposited by the female weevils 
in cavities formed by eating into the fruit of the plant. An egg hatches 
under normal conditions in about three days, and the grub immediately 
begins to feed. In from 7 to 12 days the larva or grub passes into its 
pupa stage, corresponding to the cocoon of butterflies and moths. This 
stage lasts from 3 to 5 days. Then the adult issues, and in about 5 days 
begins the production of another generation. Climatic conditions cause 
considerable variation in the duration of the stages, but on an average 
it requires from 2 to 3 weeks for the weevil to develop from the egg to 
the adult. Males and females are produced in about equal numbers. 
The males feed upon the squares and bolls without moving until the food 
begins to deteriorate. The females refrain from depositing in squares 
visited by other females. This applies throughout most of the season, 
but late in the fall, when all the fruit has become infested, several eggs 
may be placed in a single square or boll. As many as 15 larvse have been 
found in a boll. The squares are greatly preferred as food and as places 



142 APPLIED ENTOMOLOGY 

for depositing eggs. As long as a large supply of squares is present, the 
bolls are not damaged to any serious extent. The bolls, therefore, have 
a fair chance to develop as long as squares are being formed." (Marlatt, 
Farmers' Bulletin 848, U. S. D. A., 1917). 

These insects are extremely prolific. It has been calculated that from 
a single pair of the beetles in spring there might be 12,755,100 progeny by 
the end of the season, but many factors prevent this from actually being 
the case. Infested squares soon drop off the plant and on the ground 
generally become so heated as to kill the larvse in them. Parasites and 
other enemies, particularly ants, attack the insect, and other minor 
factors are of some value. All of these combined, however, only prevent 
a bad condition from becoming worse, and control measures must be 
resorted to. 

Control. — There are several control measures which seem to give par- 
tially satisfactory results. One of these is to destroy all infested plants in 
the fall, particularly in the southern part of the area where the weevil is 
found. This kills great numbers of adults about ready to hibernate, many 
more still in early stages in the plants, leaves no food for those escaping, 
and prevents the production of the latest beetles, thus reducing the num- 
ber to hibernate. It also permits fall or winter plowing which is good 
farm practice in cotton growing. Generally this destruction of the plants 
should occur in October, even though a little cotton is lost in this way. 
The destruction of any hibernating weevils wherever possible is advan- 
tageous. Crop rotation is also desirable, as many of the weevils winter 
near the cotton fields and do not fly far in the spring. Any methods 
which will hasten crop production, such as fertilizers, the use of 
early maturing varieties and early planting, are desirable. Dusting 
the young plants with arsenate of lead or arsenate of lime blown 
directly onto them has frequently given good results. The use of all 
these methods together gives considerable relief from the attacks of this 
pest, and the problem how far to go in carrying them out is largely one of 
their cost as compared with the value of the cotton which will be saved by 
the treatments. Hand picking of the weevils and of infested squares has 
not generally proved successful. As the insect has thus far been known to 
feed only on cotton and the wild cotton of Arizona (where it probably 
does not yet occur), the danger of its increasing on other food plants does 
not at present seem to exist. 

The White Pine WeevU {Pissodes strobi Peck). — This native enemy of the 
pine occurs practically wherever the white pine is found, viz., from New Bruns- 
wick and Canada west to Minnesota, and south to North Carolina. It also 
attacks our other native pines and the spruces somewhat. 

The adults (Fig. 136) pass the winter in protected places, possibly in the 
ground, and in spring gather on the terminal shoots (leaders) of the pines, generally 
on the trunk leader in preference to those of the branches. Here, near the tip, 



THE COLEOPTERA 



143 



they feed on the bark and soon cut tiny holes in it, placing their eggs in the holes. 
The borers which hatch from these eggs tunnel downward through the leader 
(Fig. 137) and by August have finished feeding and pupate in the tunnels. After 
transformation to the beetle has been completed, these escape to the outside by 
making round holes through the stems they are in. Later they hibernate for the 
winter. 

The adult beetle is about a quarter of an inch long, reddish-brown or some- 
what darker, with a white spot on each elytron not far from its outer end, which 
when the elytra are at rest brings these spots 
not far from the end of the body. There 
are also several irregular areas on the elytra 
somewhat lighter than the ground color. 

Control. — Spraying the leaders before the 
beetles gather on them in the spring, with 
arsenate of lead, using one pound more than 
the standard formula for the paste, is one 
method of control. Collecting the beetles 
after they have begun to gather on the 
leaders is also' practiced, jarring them off into 





Fig. 1.36. Fig. 137. 

Fig. 136. — Adult White Pine Weevil (Pissodes strobi Peck), enlarged nearly three 
times. {After Felt: N. Y. State Mus. Mem. 8.) 

Fig. 137. — Work of White Pine Weevil in terminal twigs of pine. {After Felt: N. Y. 
State Mus. Mem. 8.) 

a net held beneath, as they generally drop instead of flying when disturbed 
then. This treatment should be repeated several times at 4 or 5-day intervals. 
It can hardly be done except on small trees. 

The injury caused by these insects aside from their feeding, is the killing of the 
leader which stunts the growth of the tree. Usually a side branch grows up to 
replace the lost leader and makes the tree deformed, or when two do this, a fork 
is produced. In either case the value of the tree either for timber or as an orna- 
ment is largely lost. The work of the weevil is most serious and also most 
frequent on young trees, making its injuries more serious on this account. 

The Alfalfa Weevil {Phytonotnus posticus GylL). — This European insect was 
discovered in this country about 1904 and is now found in parts of Utah, Idaho 
and Wyoming, and is gradually spreading. The adult (Fig. 138) is a snout 
beetle only about three-sixteenths of an inch long, brown when fresh but almost 



144 



APPLIED ENTOMOLOGY 



black after a time. It winters as the adult close to the ground or in crevices 
there, and in some cases under rubbish, and in severe winters many are killed by 
the cold. As soon as warm days come the weevils become active and lay eggs 
in the dry alfalfa stems, before the regular laying season, and the larva? from these 
eggs attack the young plants, often causing serious injury. The weevils also feed 
on the plants quite freely at this season. After a few weeks the true egg-laying 
period begins and the adults now puncture the Hving alfalfa stems and lay their 
eggs in them, this process usually being finished by the tenth of June, though a 
few eggs are laid much later. The eggs hatch in about ten days and the larvae 
(Fig. 139) consume the alfalfa leaves, those from the ones laid early beginning to 






Fig. 138. Fig. 139. Fig. 140. 

Fig. 138. — Adult Alfalfa Weevil {Phijlonnmus posticus Gyll.) much enlarged. {From 
U. S. D. A. Bur. Ent. Bull. 112.) 

Fig. 139. — Side view of larva of Alfalfa Weevil, greatly enlarged. {From U. S. D. A. 
Bur. Ent. Bull. 112. 

Fig. 140. — Cocoon of the Alfalfa AVe.evil, greatly enlarged. {From U. S. D. A. 
Bur. Ent. Bull. 112.) 



feed in May, while later individuals are feeding until into July or even August, 
with some stragglers later. The larval period varies greatly, but an average 
length of time in this stage would be perhaps a month. When full-grown the 
larva goes to some protected place such as a dry, curled leaf or dead vegetation 
near the ground and spins a cocoon (Fig. 140) in the form of a loose network, in 
which it pupates. This stage lasts about 10 days before the appearance of the 
beetle. In late summer these beetles begin to look for winter shelter and in this 
search may spread some distance. In spring a somewhat similar flight in search 
of food, also increases their spread. This insect feeds on various species of clover 
in addition to alfalfa, and as it seems to be persistently spreading, it must be 
considered a menace to nearly all parts of the country. 

Control. — The most serious injury to the crop is that caused by the spring 
feeding before the first cutting, and this also delays the production of the second 
crop. Any treatment of the field, such as disking it with a harrow, which will 
hasten growth at that time will be a gain. Spraying these fields with arsenate of 
lead, 1 lb. of the paste in 50 gal. of water, appears to reach many of the insects 
and be quite effective. Pasturing during the spring months, dividing the fields 
so that each piece may be grazed close about once every 2 weeks, and continuing 
this until most of the eggs of the weevil have been laid, has also given good 
results, as has cutting and feeding the crop before the eggs hatch. Spraying 



THE COLEOPTERA 



145 



the stubble after the first cutting, or treating such fields by going over them once 
or twice with a disk or spring-tooth harrow, followed by dragging with a brush 
drag, to give a dust mulch, will protect the second crop but is probably less valu- 
able than the earlier spring methods. 

The Potato Stalk Weevil (Trichobaris trinotata Say). — This pest of the potato 
is widely distributed over the United States east of the Rocky Mountains except 
in the more northerly States. It has also been reported from California. The 
beetle is gray with a black head and three black spots at the base of the elytra and 
is about a fifth of an inch long. It winters in the old potato stalks and when the 
young potato plants are large enough it makes small holes in the stalks and 
sometimes in the branches, in which the eggs are deposited. The eggs hatch in 
a week or 10 days and the grubs burrow downward toward the roots and after 
reaching them turn upward again, enlarging the burrows. This tunnelling 
weakens the stalks and causes the plant to wilt and die. Pupation takes place in 
the stalks, usually near the ground, and the adults are produced in from 1 to 2 
weeks, but generally do not leave the stalks until the 
following spring. A number of individuals may be present 
in a single stalk. Other food plants are Jamestown weed, 
horse nettle, eggplant and other plants of the family 
Solanacese. 

Control. — Where the plants have wilted and dying leaves, 
and an examination of the stem shows borers to be present, 
pulling up and burning infested stalks is desirable. Prac- 
tically the same result may be obtained by collecting and 
burning all the stalks as soon as the crop has been dug, thus 
destroying the weevils in them. The destruction of all 
weeds around, which are liable to be infested by the insects, 
this work being done after the egg-laying season is over, is 
also desirable. 

The Sweet Potato Weevil (Cylas formicarius Fab.). — 
This is a tropical insect which was first reported in the 
United States about 1875. It now occurs in the most 
southerly States from Georgia to Texas, attacking the 
sweet potato. The adult (Fig. 141) unlike the other snout 
beetles here considered, is very slender, about a quarter of an inch long, with 
a black head, reddish prothorax and legs, and dark blue elytra. The prothorax 
is strongly narrowed, forming a noticeable "waist" for the insect. 

The eggs of this pest are laid singly in small holes eaten in the stem or any 
exposed potato. They hatch in a few days and the grubs in the stems burrow 
through them down to the potato, then tunnel irregularly about, becoming full- 
grown in 2 or 3 weeks. The grub now forms a cavity and in this it pupates for 
about a week and then a few days later eats its way out and may leave the potato, 
or may remain there and lay eggs for another generation in the same potato 
in which it itself developed, and this process may continue until the entire 
potato is destroyed. As long as food is available, one generation after another is 
thus produced, but when no more can be found the adult insects live along for a 
considerable time without feeding, attacking the plants and laying their eggs in 
them whenever more appear. Adult beetles feed on the leaves and stems somewhat. 

10 




Fig. 141.— Adult 
Sweet Potato Weevil 
{Cylas formicarius 
Fab.) enlarged over 
five times. (From 
U. S. D. A. Farm. 
Bull. 856.) 



146 



APPLIED ENTOMOLOGY 



As soon as tunnels in the potato are formed, the tissues around them change 
color and decay soon follows, so that an attack quickly ruins the value of the 
crop. 

Control. — Sweet potatoes found infested ever so slightly should immediately 
be destroyed, either by feeding to stock or in some other way. If any area 
becomes infested no sweet potatoes should be planted there for several years, 
and as it is probable that the insect can also breed in the wild morning glory, all 
plants of this species should also be destroyed as far as possible within the area. 
Spraying the plants with arsenate of lead or other stomach poison, applied as soon 
as the beetles appear has recently given encouraging results. Following sprays 
at about ten-day intervals may be given if necessary. 

Family Ipidae (formerly Scolytidae) (Bark beetles or Engraver beetles) . 
The members of this family are borers and nearly all attack the inner 
bark or wood of trees. They are small insects, from one twenty-fifth 
to two-fifths of an inch long, 
brownish or blackish in color, 
and usually with cylindrical 
bodies (Fig. 142). In habits 
they form two chief groups. In 
the so-called Ambrosia-beetles 
the tunnels extend through the 
wood and the young develop 
there: in the True Bark-beetles 
the tunnels are formed either in 
the inner bark or between this 
and the wood. The adult in 





Fig. 142. FiG- 143. 

Fig. 142.— Adult Bark Beetles, greatly enlarged. {Modified From Felt: iV. Y. State 
Mus. Mem. 8.) 

Fig. 143. — Work of Bark Beetles on inside of bark, slightly reduced. (Original.) 

either case cuts a tunnel slightly larger than itself in to the inner bark 
or through this, but the Ambrosia-beetles continue it on, into the 
wood. The Bark-beetles having arrived at the desired depth, turn and 
excavate one or more channels between the bark and the wood, which 
become the egg tunnels. Along the sides of these the eggs are deposited, 
either singly in little hollows, several together in larger excavations, or 



THE COLEOPTERA 147 

many in grooves of the tunnel. The larvae, on hatching, excavate tun- 
nels for themselves, leading away from the egg tunnel (Fig. 143) and 
becoming larger with the growth of the larvae. Pupation is at the end 
of the larval tunnel in a somewhat wider portion and after transforma- 
tion the adult bores its way to the outside. In the case of the Ambrosia- 
beetles a fungus used as food by the insects, grows on the walls of the 
tunnels and generally turns these walls black. 

Destruction by these insects is mainly of forest and shade trees. As 
nearly all the bark-beetles appear to prefer dying bark in which to live, 
the refuse of cutting operations, commonly termed "slash," will provide 
much of this, and most of the insects will work there. When slash comes 
to an end, however, by operations ceasing in that area, the increased 
abundance of the insects due to abundant slash often forces them for 
lack of other material, to turn to the healthy trees, themselves changing 
thereby from "secondary" to "primary" foes. Slash should therefore 
be destroyed before beetles in it can develop to the adult condition. Fire 
in forests produces many dead and weakened trees also, frequently lead- 
ing to insect attacks, and epidemics, either local or quite widespread, 
may thus result. Many trees when the beetles bore into them, pour 
out their sap or resin, and some of the insects may easily be 
drowned in this. If attacked by multitudes, however, the supply of 
sap becomes so reduced that the insects coming later can accomplish 
their purpose. 

Removing "beetle trees" befoi-e the adults escape, and either remov- 
ing and burning the bark, floating the logs, or sawing the same winter and 
burning the slabs and trimmings, are some of the measures used for the 
protection of our forests against these insects. 

One species of Ipid, the Clover Root-borer, tunnels in the main 
roots of clover. Several other species attack fruit trees, usually those 
not healthy. 

The Fruit-tree Bark-beetle or Shot-hole Borer (Eccoptogaster rugu- 
losus Ratz.). — This European fruit-tree pest has now been in the United 
States about 50 years and is present nearly everywhere east of and in 
many localities west of the Mississippi River, and has been reported from 
California. It breeds in most of the cultivated deciduous fruit trees 
as well as in several kinds of wild ones. The beetle (Fig. 144) is about 
a tenth of an inch long, almost black, except the tips of the elytra and the 
legs, which are dull red. 

In the spring the beetles enter the trees and dig out egg channels one or 
two inches long, about parallel to the grain of the wood, partly in this, 
partly in the inner bark. Here, in little niches or hollows along the sides, 
the eggs are laid. These hatch in a few days and the grubs burrow, 
first directly away from the egg channel, then turning in various directions, 
extend these larval tunnel sseveral inches, and pupate at their ends. 



148 



APPLIED ENTOMOLOGY 



When the beetles have been formed there, they bore out to the surface of 
the tree (Fig. 145) and soon begin to tunnel in again, to lay eggs for a 
second, generation which in the North becomes adult before winter, 
thus giving two generations a year. In the South with its longer warm 





Fig. 144. — Fruit-tree Bark-Beetle (Eccoptogaster rugulosus Ratz.); a, Adult Beetle; h, 
side view of same; c, pupa; d, larva. Hair lines show true length. {From U. S. D. A. 
Farm. Bull. 763.) 

season, three or perhaps four generations may be produced each year, 
the adult beetle in some cases at least, wintering in the tree, while in 
others this season may be passed in the egg stage. 

Healthy trees are not often attacked except when the beetles become 
so abundant that a sufficient supply of weak or dying ones is not available. 




Fig. 145. — Exit holes of the Fruit-tree Bark-Beetle in bark of a young tree, about natural 
size. (From U. S. D. A. Farm. Bull. 763.) 

In healthy trees the flow of gum sometimes prevents the development of 
larva3 but in time this becomes less and the insects then have a weakened 
tree to attack. Trunk, branches and twigs are perhaps equally liable to 
be injured. The burrows extending in all directions, partly in the outer 



THE COLEOPTERA 149 

surface of the wood, partly in the inner bark, destroy the cambium or 
growing layer, often entirely girdling the twig, branch or trunk as the 
case may be, and causing its death. 

Control. — This must largely be accomplished by measures to keep 
the trees as vigorous and healthy as possible. Any injured, broken 
or otherwise affected limbs should be removed or so treated if possible, 
as to restore them, and close watch of trees outside the orchard, liable to 
infestation, should also be given. Infested trees which are still pouring 
out gum can sometimes be saved by cutting back strongly and then culti- 
vating and fertilizing freely. In some cases a thick coat of whitewash 
mixed with a little table salt can be applied as a repellent for the beetles. 
This treatment sometimes needs to be applied three times — once in 
spring, again in midsummer, and once again in the fall. Washes of soap 
and carbolic acid have occasionally been used with some success, and it is 
claimed that the larvse can be killed in their burrows by using a carbo- 
lineum spray material. This is made by dissolving 3 lb. of naphtha 
soap in 3 gal. of hot water; adding a gallon of carbolineum, stirring 
thoroughly and then diluting for use at the rate of 1 part of this to 4 
of water. 

These methods should work equally well for any of the barkbettles 
where the bark is no thicker than at the places where these insects 
attack the fruit trees. 



CHAPTER XX 



THE STREPSIPTERA 



These tiny insects are seldom seen except by entomologists, and 
their parasitic habits aid in their concealment. For a long time opinions 
were divided as to where they belonged, some regarding them as a 
family of aberrant Coleoptera, while others considered them as forming 
an order. Recent studies seem to confirm the latter view and the 
group is now generally rated as a separate order, though its closest 
relations are probably with the beetles. 

The Strepsiptera, from the meaning of this name, may be called the 
Twisted-wing Parasites, though the words stylops and stylopid are fre- 
quently used in referring to them. The males on reaching the adult 
condition (Fig. 146), become free and can fly. The females on the other 




Fig. 146.- 



-Male Strepsipteron {Xenos vesparum Rossi), rather more than six times natural 
size. {After Pierce.) 



hand, remain partly within the bodies of their host insects and are worm- 
like or grub-like (Fig. 147) in appearance. The males are very small, 
soft-bodied animals, ranging from about one to perhaps four twenty- 
fifths of an inch in length. The eyes are more or less stalked and the 
antennae have one or more segments elongated on one side. The mouth 
parts are greatly modified but appear to be of the chewing type, though 
the adult does not feed. On the mesothorax is a pair of tiny clubs, some- 
times rather flattened, which represent the front pair of wings. The 
metathorax forms nearly half the entire length of the body. It bears a 
pair of well developed wings which are broad and fold lengthwise when at 
rest. The abdomen is composed of ten segments. The females are 
soft and resemble a rather long sack bearing traces of segmentation, and 
at one end a constriction, beyond which is a sort of knob, believed to be a 

150 



THE STREPSIPTERA 



151 



combination of the head and thorax; a cephalothorax in fact. This 
portion of the body is pushed out between two of the body segments of 
the host during the latter part of the metamorphosis, thus becoming 
external (Fig. 147) and the body of the host is distorted in this way. 
The members of this order may be characterized as follows: 
Tiny insects ivhich from the first larval instar to the adult, are internal 
parasites in other insects. The male adult has stalked eyes, mouth -parts of 
the chewing type, hut little or not at all developed; antennce with one or rnore 
segments prolonged laterally; pro- and mesothorax small, the latter with a 
pair of small clubs corresponding to the fore wings of most insects; nieta- 
thorax long, forming at least half the length of the body and bearing a pair of 




Fig. 147. — Female Strepsipteron, top and side views and a Stylopized Wasp: a, end 
of the parasite projefting between the abdominal segments of the Wasp. All greatly 
enlarged. {After LeuckarV s Wandtafeln.) 

broad wings which fold longitudinally. The female adult is worm-like, 
without feet, and located within the body of its host except for a cephalothorax 
which protrudes between two abdonmial plates of the latter. It is enclosed 
by its pupa skin. Metamorphosis complete. 

These insects, often called "stylops," are parasitic only in some 
Orthoptera, Homoptera, Hemiptera and Hymenoptera, as far as known, 
and at the present time only Gryllotalpa in the Orthoptera and Chryso- 
coris in the Hemiptera are known as hosts in those groups. Most of the 
parasitism is of leaf-hoppers, wasps and the solitary bees, and these 
are so disabled by the removal of their body fluids by the parasites that 
"stylopized" individuals are unable to reproduce and are greatly lacking 
in vitality. Their bodies are often distorted also and other changes are 
produced. 



152 APPLIED ENTOMOLOGY 

The eggs of the stylops appear to hatch within the body of the mother 
and the young escape by passing from the body out into the space between 
this and the pupa case of the parent in which it remains, and then through 
an opening in this at the cephalothorax, thus reaching the open air. 
They are now on the body of the parental host and this insect may carry 
them to its nest, where if it is a colonial form, the stylops may find young 
to attack there. It is generally probable though, that they leave the 
parental host at some place (possibly a blossom) where other insects of 
the host species will be liable to visit. Transferring onto such individuals 
as chance may permit, the stylopids finally arrive where larvae of the 
proper species are available, and at once attack them. Thus far they 
have been active little six-legged larvae, but after burrowing into the 
body of their host larvae they change greatly, becoming worm-like and 
legless. The males finally enter a pupa stage, after which the adults 
escape, but the females remain throughout the rest of their life in the 
bodies of their hosts. 

Where stylopids are abundant and attack injurious species of insects, 
such as are most at least of the Homoptera, the stylopized individuals, 
being unable to reproduce, become of lessened importance and their 
parasites must be considered as beneficial. Most of the Hymenoptera 
they attack, however, are beneficial and parasitism in such cases can 
hardly be considered helpful to man. The group is not sufficiently 
abundant though, to be an important factor under ordinary conditions, 
as only about a hundred species are known, but these are widely dis- 
tributed over the globe. 



CHAPTER XXI 
THE THYSANOPTERA 

The Thysanoptera — sometimes called Physapoda — are very small 
insects, peculiar in many ways. The common name for members of 
this group is Thrips, unchanged in spelling whether one or many are 
referred to. 

As a whole these insects appear to have some affinities with the hemip- 
teroid groups (Anoplura, Hemiptera and Homoptera) yet to be consid- 
ered, but are generally looked upon as forming an order by themselves, 
though in some regards they seem to have certain relations to the Cor- 
rodentia and Mallophaga. It is not improbable that they form a group 
originating not far from the common trunk of all 
the above-named orders. 

Thrips vary from one-fiftieth to one-third 
of an inch or more in length. Their mouth 
parts (Fig. 148) form in part a short, stout cone 
attached far back on the underside of the head, 
composed of the labrum, a portion of the maxillae, 
and the labium. Within this cone are three 
bristles consisting of the lobes of the maxillae and 
one mandible, the other not being developed. 
The animals are sucking insects. Four wings p^^ i48.— Side view of 
are usually present, rather long and narrow, with the head and prothorax of 
few veins, and fringed behind and generally in l^'il'^'rlrnV'^rTA. 
front also, with slender hairs, longer than the Bur. Ent. Bull. 68 Part 2.) 
breadth of the wing itself. When at rest the 

wings lie flat on the top of the abdomen. In some cases they are greatly 
reduced in size or may even be wanting entirely. The tarsi are com- 
posed either of one or two segments, usually the latter: at the tip is a 
bladder-like portion which can be drawn into the segment or pushed 
out. The abdomen consists of ten seginents, the last either conical or 
tubular in form. 

Summarizing these facts, the adult Thysanoptera may be described as: 

Small insects with greatly modified mouth parts forming a cone attached 
to the hack part of the head beneath and used for sucking. Wings four, 
generally present, long, narrow, with few veins, and fringed behind {usually 
in front also) with long hairs. Tarsi of one or two segments, the tip with a 
bladder-like swelling capable of being drawn into the tarsus. Abdomen of 
ten segments, the last either conical or tubular. Metamorphosis incomplete 
but approaching completeness. 

153 




154 APPLIED ENTOMOLOGY 

Thrips feed on plant juices, puncturing the tissues and extracting 
the sap, leaving white marks or streaks where the cells without their 
juices have dried. They attack stems, leaves and blossoms, in the last 
case often blighting them and preventing the setting of fruit. On leaves 
of plants the under surface appears in most cases to be the preferred 
place of attack and the insects do not move about much. With grasses 
and cereals the stems as well as the leaves suffer, thus checking the growth 
of the top, and in some cases the kernels of growing grain are also fed 
upon. Some species live under loose bark and a few have been reported 
as feeding upon other insects. In many cases the injury caused by these 
insects is very serious. 

In one section (Suborder Terebrantia) the female has an ovipositor 
with which she saws slits in the epidermis of plants, placing an egg in 
each slit. In the other section (Suborder Tubulifera) there is no ovi- 
positor and the eggs are laid upon the surface of the food material. The 
larvae considerably resemble the adult. After from two to four molts 
they leave their food to find some more protected place and there molt 
again, at which time wing stubs appear and other changes can be seen. 
Another molt and now the insect becomes quiet unless disturbed, not 
feeding, and marked changes become evident, bringing it more nearly 
like the adult, and the completion of these changes is followed by a molt 
which produces the adult itself. This is more than a typical incomplete 
metamorphosis, yet not entirely comparable with a complete one. It 
may be regarded therefore as intermediate between the two. 

In some cases parthenogenesis, i.e., the production of the next gener- 
ation by unfertilized females, occurs. This is perhaps to some extent 
determined by weather conditions, in this group. Parthenogenesis is 
frequently present here and there among insects and will be considered 
more fully elsewhere. Driving rains are very destructive to all kinds of 
Thrips. Lady beetles and other insects of several species feed freely 
upon them. 

The Wheat or Strawberry Thrips (Frankliniella tritici Fitch). — This 
is probably the most widely distributed species of the group in this 
country. It feeds on wheat, strawberry, apple and many other plants and 
where the blossom is attacked as in the case of the strawberry, it is blighted, 
preventing the formation of the fruit and producing the stunted struc- 
tures known as "buttons," instead. Leaves attacked often curl and be- 
come malformed, the particular parts injured soon turning brown and 
dying. In California it is a particular pest of alfalfa. 

The adult is about a twentieth of an inch long, yellowish in color. In 
the warmer parts of the South it is more or less active at all seasons of 
the year, but in the North it winters in protected places, many probably, 
like other species, in grass fields close to the ground. 

The life history in the South requires about 12 days but is probably 



THE THYSANOPTERA 



155 



longer in the cooler temperatures of the northern states, and several genera- 
tions are produced in a season. 

Control. — In general, spraying with nicotine sulfate 40 per cent, 
standard formula, or with kerosene emulsion, 1 part in 4 parts of water, 
is a good treatment. Success with these materials, however, depends 
largely upon the thoroughness of the application and the number which 
are killed. A favorite formula in California consists of 13^^ gal. of com- 
mercial lime-sulfur, and 33^^ fl. oz. of nicotine sulfate 40 per cent in 50 
gal. of water, applied as a spray. Where the adults are wintering in grass 
fields and it is practicable, burning these over will 
destroy many. 

The Onion Thrips {Thnps laoact Linde.^. — This 
pest is present practically everywhere in Europe 
and the United States, having first been noticed 
here about 1872 (Fig. 149). The adult is about a 
twenty-fifth of an inch long, rather light yellow, 
but turning brown as it becomes older. It feeds 
on a great variety of plants but being the species 
which is particularly injurious to growing onions, 
is generally known as the Onion Thrips. The onion 
leaves are whitened by the removal of their juices, 
and soon begin to bend sharply downward, and 
later they may curl or twist and even die, an area 
much affected in a field being noticeably pale 
colored and the plants stunted, while the bulbs 
make little growth. 

Winter in the North is spent as the adult in 
protected situations such as in dead grass close to 
the ground or in rubbish left on the field. In 
spring the young onion plants are attacked soon 

after they come up, first in the bud, later on the leaves, in which the eggs 
are laid. The life cycle from egg to adult is influenced by the tempera- 
ture, varying from a little less than 3 weeks to over a month, and in 
the most southerly states the generations overlap so that practically all 
stages may be found at the same time. Sometimes in the North this 
insect becomes a greenhouse pest on roses, carnations, cucumbers and 
tomatoes, though the Green-house Thrips {Heliothrips hcemorrhoidalis 
Bouche) is most often responsible for this injury. 

Control. — Any methods of farming which will reduce the oppor- 
tunities for this insect to pass the winter successfully, are of value. The 
destruction of all refuse on the field after the crop has been gathered: 
fall plowing of such fields, and burning over grass lands adjacent to them, 
at the proper time in the spring, are all beneficial. Cultivation and fertili- 
zation to push the crop ahead early to "keep it ahead of the thrips" is 




Fi(i. 140. -Nymph 
of the Onion Thrips 
{Thrips tabaci Linde.), 
greatly enlarged. 
(From Britton : Third 
Rcpt. Conn. State 
Entomologist.) 



156 



APPLIED ENTOMOLOGY 



also helpful. Spraying the plants with nicotine sulfate 40 per cent, 
% pint., 4 lb. more or less of soap, and 50 gal. of water is a fairly- 
effective treatment. Fish-oil soap is better than laundry soap when 
obtainable, and the amount to use is determined by spraying a leaf with 
the mixture. If the spray gathers together into larger drops, leaving 
parts of the leaves dry, more soap is needed, for its use is mainly as a 
"spreader" over the leaf surface. This treatment should be repeated 
every 8 or 10 days as long as the Thrips are present in any abundance, 
until within a month of harvesting. Use a fine, misty spray with con- 
derable pump pressure. Only thorough spraying will give effective 
results. 

The Pear Thrips {TcBniothrips inconsequens Uzel). — This insect was 
first discovered in the United States in the central part of California, 




Fig. 150. 



-Adult Pear Thrips (Tceniothrips inconsequens Uzel), greatly enlarged. 
U. S. D. A. Bull. 173.) 



{.From. 



attacking deciduous fruit trees, particularly pears, prunes and cherries, 
blighting the blossoms by the abstraction of their sap. Later it was found 
in British Columbia, in the Hudson River Valley in New York, and still 
later in Pennsylvania, Maryland, and in England. Recently it has been 
learned that the insect was first discovered in Bohemia, feeding in 
blossoms. 

The destruction caused by this pest in Cahfornia has been very great 
some years. The crop of prunes in the Santa Clara Valley alone has 
been estimated as having been reduced in the 7 years, 1905 to 1911, 
141,000,000 lb. The injury is caused by the feeding of the young and 
adults on leaves, buds, fiowers and fruit, and by laying eggs in the leaves 
and fruit stems and also in the small fruit. 



THE THYSANOPTERA 



157 




The dark brown — almost black — adults (Fig. 150) appear early in 
spring, coming out of the ground about the time the fruit buds are swelling 
and opening, and as soon as these have opened slightly the insects work 
their way into them and feed on the most delicate parts. The eggs are 
laid mainly in the young leaf and fruit stems and young fruit and hatch 
on an average after about 8 days. The nymphs (Fig. 151) feed on the 
leaves and young fruit forming a sort of " scab " on the surface of the latter, 
and remain on the tree for 2 or 3 weeks, though from the first young to 
appear to the last young to disappear, may be 
more than 2 months. When through feeding 
they fall to the ground, which they enter for a 
varying distance, and there, after from 2 to 5 or 
6 months, they transform to the last stage before 
the adult, having previously molted once under- 
ground. Late in the fall or winter the final 
molt produces the adults which remain in the 
ground till early spring. 

This remarkable life history, quite unlike 
anything known for any other Thysanoptera, 
permits but one generation a year, with active 
injury during only a rather short period in the 
spring. 

Control. — These insects can be destroyed by 
spraying with Nicotine sulfate 40 per cent used 
at the rate of 1 part to 800 parts of water, stand- 
ard formula. Success with this treatment, how- 
ever, is entirely dependent upon the thoroughness 
of the application. The first treatment should 
at once follow the discovery of the Thrips upon 
the swelling buds and should be repeated at least 
every 2 or 3 days until the buds ^.re open or 
the Thrips have become very few. No spraying 
should be done from the time the blossoms open 

until the petals fall. Then, if Thrips are abundant on the remains of 
the blossoms, another treatment should be given. 

The Citrus Thrips {Scirtothrips citri Moult.) is a rather serious pest 
in California and Arizona. It feeds upon the tender stems, leaves and fruit 
of citrus trees, and occasionally also attacks the grape, apricot and other 
plants. With seedling plants the leaves and buds are injured and 
growth is checked. The fruit is injured by scars and scabs caused by the 
feeding, and greatly reduced in value, and some drops to the ground. 

The adult is one of the smallest of the Thysanoptera, varying from 
one-fiftieth to one-twentieth of an inch in length, and is orange-yellow in 
color. The young appear in April and May and gather on the leaves 



^-i^ 



\ 




Fig. 151. — Nymph of 
Pear Thrips, greatly en- 
larged. (From U. S. D A. 
Bur. Ent. Bull. 68, Part 1.) 



158 APPLIED ENTOMOLOGY 

and fruit where they remain until the midsummer hardening of these 
parts leads most of them to leave for various other food plants, until 
August and September when they return to the citrus trees again and 
lay their eggs in the leaves and stems of the plant. These winter over 
and hatch the following spring. Following the production of adults 
from the hatching and development of these eggs, there may be six to 
eight generations during the season and all stages may be present at 
once on a tree as late as December, though these die with colder weather, 
leaving only the eggs to hatch in the spring. The last stage before the 
adult, during which the insect is quiet, is passed in crevices of the trunks 
or in rubbish under the trees, but not in the ground. 

Control. — Spraying, either with lime-sulfur wash using 1 part (if of 
a density of 33°Be.) in 50 parts of water, or with more water than this if 
the wash reads higher; or with Nicotine sulfate 40 per cent, at the rate 
of 1 part in 800 parts of water, have given excellent results. The first 
application should be made as soon as four-fifths or more of the blossoms 
have fallen, and a second 10 days to 2 weeks later. If these two treat- 
ments have been well-timed and thorough, the third can be delayed until 
about 3 weeks after the second. A fourth treatment late in August or 
early in September, if the returning insects are very abundant on new 
shoots, will aid much in checking their increase. In all treatments the 
application should be very thorough and with a pressure of at least 1251b. 
Particular attention should be given at the second application to 
completely drenching the fruit and any tender leaves. 

In addition to the species of Thrips given separate consideration 
above, nu nerous other species are frequently of some importance. 
Among these the Grass Thrips which sucks the sap from the stems of the 
lighter grasses, turning them white and killing them, thus causing "silver 
top" as it is called; the Greenhouse Thrips which attacks tomatoes, 
cucumbers and many other plants in greenhouses in the North and out- 
of-doors in the South, and the Camphor Thrips which is a serious pest 
of the Camphor tree in Florida, are perhaps the most important. 



CHAPTER XXII 



THE CORRODENTIA 



Most of the Corrodentia are very small, even tiny insects, though 
a few giants of the group found in South America have a wing-spread of 
about an inch. Some of the group are wingless and are most often 
noticed as small, whitish, gray or brown specks running over the leaves 
of old books. These are generally called Book-lice. The winged forms 
(frequently called Psocids, though this name really applies to the entire 
group) when adult are somewhat larger and 
are found on tree trunks, weathered fences 
and other places where hchens grow, and 
furnish them with their food. In general 
the members of the group eat animal or 
vegetable refuse, mould, fungi and similar 
materials. Several hundred kinds are 
known. 

The body in the Corrodentia though 
quite soft, is well developed, but the pro- 
thorax is small and concealed in some cases 
between the head and the mesothorax. In 
others it is distinct, but as the meso- and 
metathorax are grown together in those 
cases, only two of the three thoracic seg- 
ments are evident. The antennsB are rather 
long and slender, and the mouth parts are 
for chewing but considerably different in 
some details from the typical structure. 
The wings when present are four in 
number, with very noticeable veins, few of which are cross-veins. When 
at rest the hinder margins of the wings of the opposite sides are brought 
together over the back of the insect with their upper surfaces sloping 
down at the sides, thus assuming the position of a steep house roof. 
They are often more or less dusky or mottled. The tarsi consist of only 
two or three segments. Ocelli may be present in the adults but not in 
the nymphs. These are quite similar to the adults otherwise, and develop 
through a series of molts into the adult condition. 

The group may be characterized as follows: 

Small, soft-hodied insects with or without wings when adult. In those 
having wings there are two pairs, with prominent veins: when at rest they 

159 




Fig. 152. — Adult Booklouse 
about fifty times natural size. 
(From U. S. D. A. Farm. Bull. 
1104.) 



160 



APPLIED ENTOMOLOGY 



are held at a sharp angle over the body, hinder margins uppermost. An- 
tennce long and slender. Tarsi of two or three segments. Ocelli sometimes 
present in the adult condition. Metamorphosis incomplete. 

This little order contains few species of much economic importance. 
The wingless forms — book-lice (Fig. 152) — found in buildings, eat the 
paste and paper of old books and are also found in birds' nests where 
they find in feathers and other organic debris their food. The winged 
forms, frequently called Psocids, are found in various places, but perhaps 
most frequently on the trunks of trees, generally in clusters and often in 
various stages of their development. They have the power of producing 
silk and sometimes the clusters appear to be covered, at least partly, by 
a web of this. 




Fig. 153. — Adult Psocids: a, side view showing position of wings at rest; b, Psocid 
(Psocus lineatus) with wings spread. Both greatly enlarged. {From Sanderson and 
Jackson, Elementary Entmology: a, after Kellogg: b, after J. B. Smith.) 

Some of the book-lice are claimed to be able to make a ticking sound 
something like that of a watch, and this sound is often called the ''death 
watch." Such a sound is certainly produced by a small beetle, and the 
possibility of the book-lice also being able to make it has been questioned. 
The weight of evidence thus far, however, seems to favor this possibility. 
It is heard chiefly in old houses at night or when everything is quiet, as 
a faint, rapidly repeated tick-tick-tick, and is in all probability, the call 
of an insect to its mate. 

The winged Corrodentia (Psocids, Fig. 153) are not known to be of 
any economic importance. Where the wingless forms (book-lice) be- 
come extremely abundant in buildings, relief may be obtained by a 
thorough cleaning of the infested places. Light and air, particularly 
dry air, are unfavorable to them, and heating a room to quite a high 
temperature for a few hours and the exposure of all the furniture to 
sunlight for a time on a bright day will generally free the place from these 
insects. All stages except the egg appear to die at the beginning of 
winter. 



CHAPTER XXIII 

THE MALLOPHAGA 

The Mallophaga are generally called bird-lice but as they feed by biting 
off particles of feathers, hairs and scales of the skin, from the animals on 
which they live, the name biting-lice would be better as it would dis- 
tinguish them more accurately from a large number of very similar 
insects found in many cases on the same animals, which feed by sucking 
the blood of their hosts, and which are called sucking-lice. 









,^-K 




Fig. 154. 



-Samples of Mallophaga or Biting Lire, greatly enlarged: hair lines show 
actual length. (After Kellogg.) 



The bird-lice or biting-lice (Fig. 154) are very small insects ranging 
from about one-twenty-fifth to one-tenth of an inch in length, rather 
whitish in color, much flattened and with an external shell which is 
unusually hard for such small insects. They are wingless and are rarely 
found off the bodies of the birds and mammals on which they live. 
Development from the egg is gradual, through a series of molts which 
finally produces the adult. 

The group may be described thus: 

Sinall, wingless insects, usually with a large head; mouth -parts for 
biting. Body quite hard, flattened. Parasitic on the bodies of birds and 
some mammals. Metamorphosis incomplete. 

About fifteen hundred kinds of Mallophaga are known, most of them 
living on birds, where they feed on feathers and skin scales. On mam- 
mals, hairs replace the feathers as their food. When abundant, bare 
areas on the bodies of birds appear where the feathers have been eaten or 
11 161 



162 APPLIED ENTOMOLOGY 

have dropped out as a result of the feeding of these insects. Birds nor- 
mally dust themselves, working the dust in among their feathers, where 
it is claimed it gets into the spiracles of the lice and suffocates them. 
Apparently the greatest injury to the fowls does not come from the feeding 
on the feathers and scales, but from the irritation produced by the 
scratching of the skin caused by the tarsal claws of the parasites as 
they move about, and this must be quite severe, for birds considerably 
infested become dull and act sick, and are certainly less able to resist 
disease than usual. 

The eggs of the lice are attached separately to the feathers or hairs 
of the host, and hatch into nymphs, which on the whole considerably 
resemble their adults. They feed, molt, grow and become adult in a 
few weeks. 




Fig. 155. — Female Chicken Body Louse (Menopon biserialum Piag.), greatly enlarged. 
{From U. S. D. A. Farm. Bull. 801.) 

Though these insects are widely distributed on many kinds of birds 
and on a number of mammals, they are of importance from an economic 
standpoint mainly on the domesticated birds such as chickens, turkeys, 
geese, ducks and pigeons, though occasionally dogs, cattle and horses 
become infested. 

Seven different kinds of biting-lice are fairly common on domestic 
fowls. Of these, some prefer the head for their location, others the body 
(Fig. 155), etc., though not found exclusively in those locations. Four 
kinds are often present on turkeys and quite a number occur on geese 
and ducks. Pigeons and guinea fowls have several species. 



THE MALLOPHAGA 163 

Control of Lice on Poultry. — Various methods of control for poultry 
lice are in use, but in most cases at least, the best one is the use of sodium 
fluorid, dry or dissolved in water. Either the commercial or the chemi- 
cally pure grade can be used but the commercial is somewhat easier to 
work with, particularly for dusting the fowls. 

The first step in treatment is to shut up all the fowls. Then each 
bird is taken and while being held either by the wings or legs with one 
hand, pinches of the powder are placed in among the feathers, ''one on the 
head, one on the neck, two on the back, one on the breast, one below the 
vent, one on the tail, one on each thigh, and one scattered on the under- 
side of each wing when spread." For young birds dusting rather than 
dipping is advisable. 

If dipping is preferred for the older birds, use warm water in a .tub, 
measuring the water put into the tub and adding from % to 1 oz. of 
the commercial fluorid (or % oz. of the chemically pure fluorid) to each 
gallon of water. Dip the birds in this, holding the wings over the back 
with one hand and ruffling the feathers with the other, below the surface 
of the water. Then duck the head of the bird once or twice, take it out 
of the water, let it drain for a moment and then let it go. After a little 
experience, three-quarters of a minute per bird will be an ample amount 
of time for this treatment. 

The water in the tub will be reduced in quantity of course, by use, 
and more, having the proper amount of fluorid dissolved in it should be 
at hand to add from time to time. 

Whether the sodium fluorid treatment, which has only recently been 
discovered, will give satisfaction for the treatment of biting lice on mam- 
mals cannot be stated. Heretofore, washing an infested animal with 
kerosene emulsion has been advised. 

Boxes of road dust, available in poultry houses during the winter 
months for the birds to dust themselves in, are desirable. Formerly 
used to actually aid the birds in freeing themselves of lice, they now act 
as indicators that lice are present and that treatment should be given 



CHAPTER XXIV 
THE ANOPLURA 

These insects are the sucking Uce which attack mammals, and mam- 
mals only. They are small, wingless insects from about one twenty-fifth 
to one-fourth of an inch in length, and with mouth parts for sucking. The 
head is usually rather pointed in front and is often joined to the thorax 
by a distinct neck which permits its free movement. The distinction 
between thorax and abdomen is less evident, the constriction there being 
practically non-existent. The legs, which join the thorax well out on its 
sides, are constructed for climbing and grasping, and each ends in a 
single claw, so placed with reference to the rest of the leg that it can 
tightly grasp a hair, the claw on one side and the tibia on the other. 
The eyes are rudimentary or absent in some cases. 

The group may be defined as: 

Small, wingless insects with suckifig mouth 'parts, feeding on the hlood 
of mammals. Eyes present or absent. Tarsi each with one claw. Meta- 
morphosis incomplete. 







-ft ^? 




Fig. 156. — Samples of Anoplura or Sucking Lice, greatly enlarged. {After Dalla Torre.) 



Anoplura (Fig. 156) occur on man, monkeys, domestic animals, rats, 
mice, rabbits, squirrels, the elephant, etc., and one genus is found on the 
seal. The mouth consists of a flexible proboscis which may be drawn 
in or pushed out, turning inside out as it goes and exposing some chiti- 
nous hooks which attach themselves to the skin of the host. Lodged 
in the head are two long, slender, sharp-pointed structures called stabbers, 
one, possibly both, apparently double in nature but more or less fused, 
and so placed as to form a canal between them through which saliva may 

164 



TkE ANOPLURA 



165 



be injected into the wound they make. These stabbers are forced 
through the skin within the area encircled by the proboscis, saliva is 
forced into the wound and after a few moments feeding begins, the blood 
of the host being pumped into the body of the louse. 

Eggs or "nits" are laid singly, attached to the hairs of the host or in 
some species, to the fibres of the clothing. They hatch in from 1 to 2 
weeks, according to the species and the temperature, but when the 
latter remains low, as where the eggs do not feel the effects of the warmth 
of the host, they will not hatch (at least with the lice infesting man). 
The nymph stage probably requires 8 to 10 days, though practically 
nothing is known of the development except with the lice attacking 
man. Several hundred eggs are usually laid by each female during a 
period of nearly a month, so that a heavy infestation becomes possible 
in quite a brief time. 

The Anoplura is a small group of insects, probably only about a 
hundred species being known. They were formerly considered degener- 
ate Hemiptera, but with the division of the 
old Order Hemiptera into separate orders — the 
Hemiptera in a more restricted sense and the 
Homoptera — it has seemed more logical to regard 
the Anoplura as also an Order, most closely re- 
lated to these, but still sufficiently different to 
entitle it to ordinal rank. 

The Human Body Louse (Pediculus humanus 
L.). — This pest (Fig. 157), which during the 
European war also received the common name 
"cootie," is now generally regarded as being of 
two races, the head louse (formerly called Pedi- 
culus capitis) which is found chiefly on the head, 
and the body louse (ionnerly Pediculus vestimenti 
or P. corporis) found mainly on the clothing, 
rather than different species, but the races differ 
somewhat because of different conditions under 

which they live. This insect under ordinary conditions of cleanliness 
can be easily controlled, but in camp life finds an opportunity to increase, 
often almost without possibility of being checked. 

Under ordinary conditions a simple treatment for the race living on 
the head is to wash thoroughly with tincture of larkspur, which can be 
obtained of a druggist, and repeat this two or three times at intervals of 
about a week. For the race living on the body, treatment is somewhat 
different, as the pests are largely on the clothing, reaching across from this 
to the skin to feed. Here boiling all clothing which can be so treated, 
dry heating the rest to 130°F. for >2 hr. and taking a hot bath will usu- 
ally be sufficient. 




Fig. 157. — Human Body 
Louse {Pediculus humanus 
L.) about eight times 
natural size. {From 
Beilese.) 



166 APPLIED ENTOMOLOGY 

Rather recently it has been discovered that the hce of man are con- 
cerned in the transmission of Relapsing fever, Trench fever, and that 
terrible disease Typhus fever. It does not at present seem that the 
causal agents of the first two of these are actually transferred to man 
by the feeding of the infested lice, but rather that these agents are present 
in their bodies and feces, and that by scratching parts irritated, fluids from 
crushed lice or the feces get rubbed into the irritated areas, are able to 
enter the body, reach the blood and begin the disease. This also 
appears to be true in the case of Typhus fever, but here inoculation by the 
feeding of the lice also seems probable. In some cases where scratching 
does not occur but where Relapsing or Trench fever nevertheless develops, 
it is probable that the feces get into the feeding wounds and in that way 
cause the disease. 

The Crab Louse (Phthirus pubis L.). — This louse is quite different 
in appearance from the last, being smaller, shorter, broader, and with 

its legs projecting outwardly near together 
(Fig. 158). The fore legs are slender but 
the others are stout and each has a powerful 
serrated claw which shuts against a pro- 
jection of the preceding segment of the leg 
in such a way as to give a very firm grip 
on a hair. This insect is found primarily 
on the hairy parts of the body except the 
head, but in exceptional cases it may be 
found there also. It holds onto the hairs 
while feeding and in moving about always 

Fig. 158. — Human Crab Louse i i , ,- i ,i , i • • ^ ,-i •, 

{Phthirus pubis L.) about twelve holds tightly to hairs on one side until it 
times natural size. (FromBeriese.) jj^s obtained a grasp on others on the 

other side. This gives it a sideways move- 
ment which is responsible for its common name. Its life history is 
much the same as in the other species. 

Washing thoroughly with tincture of larkspur as for the head louse 
is usually an effective treatment. An ointment made of 4 parts of crude 
naphthaline mixed with 1 part of soft soap rubbed on the undercloth- 
ing in the infested region has also been found to be a very successful 
treatment. 

Lice on Domestic Animals.— These are sometimes serious in their 
attacks, weakening the animal greatly if they are abundant. In the 
treatment of these pests it should be borne in mind that poisonous 
materials cannot be used because of the danger coming from the animals' 
licking themselves. Various substances have been used for live stock, 
such as 15 per cent kerosene emulsion scrubbed on the skin; washing 
with potassium sulfid, using from 2 to 4 oz. per gallon of water according 
to the size and vigor of the animal; the application of a mixture of sulfur 




THE ANOPLURA 167 

1 part, lard 4 parts, rubbed over the body, or washing with dilute car- 
bolic acid using 1 part of the acid in 30 parts of water. The most usual 
treatment for cattle lice, however, is by the use of stavesacre (Delphin- 
ium) seeds. Four ounces of these seeds and 1 oz. of white hellebore are 
boiled in a gallon of water until only 2 qt. remain. This is then applied 
with a brush to the animals. It may need to be repeated if more lice 
■ appear, showing that eggs or some of the lice escaped the first application. 
Raw linseed oil, applied with a brush has recently been recommended as 
an alternative treatment, the material for one animal costing about five 
cents. 

The relation of insects to disease as has been brought out above, 
where lice serve to convey the germs or parasites causing illness to man, 
is one of the newer subjects in Entomology but one which has been shown 
to be of great importance. Medical Entomology is already a large field 
upon which much has been written, and yet one about which little is 
probably known in comparison with its actual size. 



CHAPTER XXV 
THE HEMIPTERA 

The Hemiptera is a large group containing many insects which are 
always injuriously active, and many more which occasionally become so. 
They vary greatly in size, some being minute while others may attain 
a length of four or five inches. They are most numerous in species in 
the warmer portions of the globe, but an abundance of individuals in 
colder regions results in making them extremely common everywhere. 

Most Hemiptera have the dorsal surface of the body rather flattened, 
though there are many exceptions to this statement, and the wings when 
not in use rest upon this surface. The wings are nearly always present, 
four in number, and the basal half, or sometimes more, of the front 
pair is thickened and horny, resembling the elytra of beetles. The outer 
end, however, is membranous and veins traverse this portion, so that the 
fore wings are appropriately called hemielytra. The membranous part 
of one wing largely overlaps that of the other when they are at rest. In a 
few families the difference in the texture of the two portions is not very 
perceptible but in most cases it is plainly evident. The hinder wings are 
entirely membranous and when not in use are concealed beneath the 
others. 

The body of the Hemipteron with few exceptions, shows no constric- 
tion at the junction of thorax and abdomen and is usually widest at the 
hinder end of the prothorax. The attachments of the wings behind 
this do not occupy anywhere near all of the width of the body, and 
directly behind the pronotum, between the wings, the space is taken 
up by a rather large, usually quite triangular plate called the scutellum. 
In some families this becomes greatly enlarged, covering more or less 
of the dorsal surface of the body from the pronotum back, and in such 
cases the wings in closing slip under this so that little besides their costas 
show. 

Hemiptera are sucking insects (Fig. 159), obtaining their food by 
piercing the surfaces of plants or animals and drawing into their own 
bodies the sap or blood. The mouth parts in the group have been identi- 
fied with those of chewing insects, but they have been greatly modified to 
form a beak or rostrum which is attached to the front of the underside 
of the head. The details of structure of the rostrum differ in different 
Hemiptera but agree in general plan (Fig. 160). The outside of the 

168 



THE HEMIPTERA 



169 



rostrum is a sheath which appears in the main to be derived from the 
labium or hinder lip of the chewing insect, being much elongated, and 
its sides rolled forward to meet or almost meet in front, forming a 
tube. The front part of this tube, however, near the head, seems not to 
be formed by the labium, leaving open a somewhat triangular place 
and the labrum or front lip appears to have grown downward to more or 
less completely close up this portion of the sheath. Within the tube 



if^ 




.Mid 



Fig. 159. Fig. 160. 

Fig. 159. — Side view of a Squash Bug {Anasa tristis De G.) showing the rostrum, 
and its attachmentto the front of the head. Some of the mouth parts usually within the 
sheath have been pulled out and show in front of it. Rather more than twice natural size. 
(Original.) 

Fig. 160. — Diagram of a cross-section of rostrum of a Squash Bug: la, labium; md, 
mandible; mx, maxilla; Sa, tube carrying saliva to the wound; su, tube through which the 
food is drawn into the body. (Modified from Tower, Am. EjU. Soc. Am. VI, 1913.) 

thus formed lie the mandibles and maxillae which have become trans- 
formed into long and slender bristles with pointed tips. The surfaces 
of the maxillae which face each other have so changed their outline as to 
form two gutters or troughs and when the maxillae are pressed together 
as is the case in the living insect, each gutter of one side coincides with the 
corresponding one of the other to form two tubes, half of each being 
contributed by each maxilla. The more anterior of the tubes is for suck- 
ing the nourishment obtained, into the bug, while the other is for inject- 
ing saliva into the wound. The mandibles lie beside the maxillae and 
seem to function chiefly as piercing organs. 

In feeding, the tip of the rostrum is brought into contact with the sur- 
face of the object to be fed upon and the tips of the mandibles and maxillae 
are then driven into it until sap or blood as the case may be, is reached. 
Then saliva is forced into the wound and this seems to be irritating or 
even poisonous in its nature and its presence in the wound causes (in 
animals at least) an increased flow of the body fluids to that point. 
Assured thus of a sufficient supply of food, sucking it into the body of 
the insect is then begun. 

The eggs of Hemiptera are laid under greatly differing conditions. 
Some are inserted in twigs or stems; others are laid either singly or in 



170 



APPLIED ENTOMOLOGY 



clusters on leaves, twigs or in other places. The eggs themselves vary 
much in appearance, some being provided with circlets of spines, some 
with long filaments and some being smooth but of unusual form or color. 
They hatch into nymphs (Fig. 161) more or less closely resembling the 
adult, which stage they reach by a series of molts, changing with each 
molt. 

The Order Hemiptera may be characterized as: 

Insects which when adult nearly always have four wings, the front pair 
in most cases partly horny, partly membranous: with a plate located between 
the bases of the wings, usually triangular in outline, in some cases covering 
more or less of the abdomen above: mouth parts for sucking, and attached to 
the front end of the underside of the head. Metamorphosis incomplete. 





Fig. 161. — Metamorphosis of the Squash Bug (Anasa tristis De G.) : adult and nymphs 
of different ages, all twice natural size. {From Folsom.) 



Hemiptera occur under almost every conceivable condition of life. 
Some live in water, coming to the surface only to obtain air: some are 
found on the surface of the water and some are found on the ocean hun- 
dreds of miles from land. Most of the group are terrestrial, however, and 
in many cases are widely distributed. Probably fifteen thousand species 
are already known but the group has been little studied as compared 
with some of the more attractively colored and marked orders. Those 
living in water are at least for the most part, feeders on insects and other 
animals small enough for them to capture : those which live on the surface 
are also predaceous, while of the land forms some consume other insects 
but probably the larger number are plant feeders. The Hemiptera are 
the true bugs, the general use of the term "bug" as applied to all insects 
being incorrect. 



THE HEMIPTERA 



171 



Family Pentatomidae. — This group consists of land forms, many of 
them producing a disagreeable odor which has resulted in applying to 
these insects the common name "stink bugs" (Fig. 162). Most of them 
suck the sap from various plants, leaving behind the odor so often 
noticeable on berries. Others are carnivorous, attacking caterpillars and 
sucking their juices. Many of them are minor pests and potentially 
important ones, and their fair size — often half an inch or more in length — 
together with considerable width, giving them a broad surface, makes 
them fairly familiar objects. 






Fig. 162. Fig. 163. Fig. 164. 

Fig. 162. — Pentatomid Bug (Euschistus), natural size. (Original.) 
Fig. 163. — Adult Harlequin Bug {Murgantia hislrionica Hahn.), slightly enlarged 

(Original.) 

Fig. 164. — Eggs of Harlequin Bug, slightly enlarged. (Modified from, Essig. Inj. 

and Benef. Ins. Cal.) 

The Harlequin Bug (Murgantia histrionica Hahn). — This pest, 
native to Mexico and Central America, has gradually spread northward, 
feeding on cabbage, kale, mustard, turnip, radish and other cruciferous 
plants, and its present northern limits are now in New Jersey and Long 
Island, Ohio, Indiana, Wisconsin, Iowa, Nebraska, Colorado, Arizona, 
Nevada and Washington, though the insect rarely does much injury so 
far north. 

The adults (Fig. 163) are about half an inch long, black or dark blue 
with bright red or orange marks, the brilliancy of the colors making the 
insects very noticeable and resulting in the common names "calico- 
back," "terrapin-bug" and perhaps "fire-bug" as well. They winter in 
the adult stage under rubbish or wherever they can find protection, 
though in the far South they are more or less active nearly all the time 
and there the nymphs are also present then. 

Farther north the bugs become active during the early spring and 
attack various wild cruciferous plants and lay their eggs (Fig. 164). 
These are usually placed in clusters of about 12, in two rows, and are 
somewhat barrel-shaped, white, with two black rings around each, and a 
third ring on the upper end, being both very noticeable and distinctive. 
They hatch in from 3 to 11 days according to the temperature and the 
nymphs suck the sap from the plants for 1 to 2 months, again according 



172 APPLIED ENTOMOLOGY 

to the temperature, before becoming adult. When cabbage, cauliflower, 
kale, turnip, radish, etc., become available, the bugs go to these and there- 
after devote their attention to these plants until late in the fall when 
various other kinds, such as egg plant, asparagus, tomato, beans, beets, 
etc., may be attacked. 

Control. — Insecticides which do not injure the plants the bugs are on, 
are not usually effective against this pest and preventive methods have 
thus far given the best results. Planting a very early crop of kale, 
mustard or rape, to which the bugs when they first become active in 
spring may be attracted, is a good practice, for the insects seem to prefer 
these to the other plants. Here the bugs may be killed by spraying with 
kerosene, collected in nets and destroyed, or may be burned with a torch. 
The few that may escape this treatment can be picked by hand wherever 
found, but if the trapping method above is followed, few usually escape. 

Clean culture is also helpful. As soon as the crops are gathered all 
the stalks and leaves of the plants on which the Harlequin bug feeds 
should be gathered and destroyed, both to leave them no food and to 
remove possible places where they might winter. Rubbish which might 
provide wintering quarters should also be carefully removed. Recent 
tests with contact insecticides show some possibility that control by 
these materials may be obtained, but this subject has not yet been suffi- 
ciently investigated to warrant definite recommendations. 

Family Cydnidae. — The bugs of this family are usually of little eco- 
nomic importance. Some of them are interesting, however, as in them the 
scutellum, usually quite small, becomes greatly enlarged, covering nearly 
all of the thorax and abdomen behind the pronotum. In one genus the 
insects are nearly circular in outline, very convex, having much the form 
of lady beetles, and are generally glistening black, in a few cases with a 
narrow line of white. These are often called "negro-bugs" and one 
species feeds on small fruits and leaves a disagreeable odor. 

Family Coreidae. — Many of the members of this large family are of 
considerable size for bugs, some being over an inch long, but their bodies 
are much more narrow in proportion to their length than in the Penta- 
tomidaB. Some of the southern species have broad, flat expansions of the 
tibiae, giving them a curious appearance. The insects of this group suck 
plant juices and a number are frequently more or less injurious to various 
plants. 

The Squash Bug (Anasa tristis De G.). — The Squash Bug is common 
almost everywhere in the United States feeding on squash and pumpkin 
and sometimes on cucumber and melon plants (see Fig. 161). The adult 
is a dark brown bug, very flnely mottled with gray or lighter brown in 
many cases, about three-quarters of an inch long. It winters as the 
adult under rubbish or in other protected places, and appears in spring, 
ready for its food plants when these come up. When the leaves of the 



THE HEMIPTERA 173 

plants develop the bugs lay their eggs on their under surface in clusters 
which vary greatly in the number of eggs composing them. The eggs 
themselves are oval in outline, very convex, and being resin-brown in 
color are very conspicuous against the green background of the leaf. 
In a cluster the eggs are not usually so laid that they touch, but somewhat 
spaced apart in most cases. At intervals before and during the egg- 
laying period the adults feed on the plants and when they are very abun- 
dant may seriously injure or in some cases even kill them. 

The eggs hatch on an average in about 10 days and the tiny nymphs, 
green and reddish in color, begin to suck the sap from the under side of the 
leaves, at first together, but scattering later. The reddish color of the 
nymph quickly changes to black and the green gradually becomes more 
of a gray. Feeding and molting five times results in the production of 
the adult after a period of from 4 to 5 weeks from the time the eggs 
hatch, and in the North the adults feed on the plants until fall; then 
go into winter quarters. In the South the longer seasons which permit 
an earlier start in the spring and the higher temperature which causes 
the eggs to hatch more quickly, permit the production, in some cases at 
least, of two generations each season. 

The injury to the plants caused by the spring feeding of the adult is 
continued by the sucking of the young. Where these are plenty, growth 
is checked and the crop reduced. If the plants are killed by frost before 
the nymphs are mature, they often attack the fruits in order to obtain 
the nourishment they need to become adult. 

Control. — Contact insecticides are not effective for the adult Squash 
bug, which has an unusually thick shell. The usual methods for conti'ol are 
the removal as far as possible of all rubbish and places where the insects 
can obtain protection during the winter; stimulation of growth of the 
plants by fertilizers and cultivation; protection of the young plants by 
fine netting until they are so well started that they can thrive despite the 
bugs; traps of bark or shingles placed close to the plants, under which the 
bugs gather at night and whence they can be gathered and destroyed 
early in the morning (this can be begun even before the plants are up) ; 
egg-masses being easily seen can be quickly found and crushed; and while 
the nymphs are small, spraying with Nicotine sulfate 40 per cent, 1 part 
in 400 of water will destroy thern. The difficulty in reaching the nymphs 
on the under side of the leaves with the spray, can in part be obviated 
by attaching the nozzle of the spray pump to a piece of tubing connecting 
at its other end with the hose, and bent in a loop so as to give an upward 
spray. 

In the South one or two very closely allied species also attack the 
squashes and cucurbits and may be controlled in the same ways. 

Family Pyrrhocoridae. — The insects of this family superficially re- 
semble the Coreids and are of medium size. Only one is of any economic 



174 



APPLIED ENTOMOLOGY 



importance in the United States, and that in only a few of the Southern 
States though it is also injurious in some of the West India Islands. 
The Cotton Stainer {Dysdercus suturellus H.-S.) as it is called (Fig, 165), 
feeds on cotton, and occasionally the egg plant and orange among culti- 
vated crops. On oranges it attacks the fruit about the time it is ripen- 
ing, puncturing the skin and thus hastening decay. On cotton the insect 
punctures the partly developed bolls and if the attack is severe these 
may be destroyed. If not, the fiber is more or less stained, apparently 
from the punctures in the seeds, reducing the value of the cotton 
anywhere from 5 to 50 per cent. As the bugs develop in colonies and 
remain close together for some time and in their early stages are red, they 




Fig. 165. — The Cotton Stainer {Dysdercus suturellus H.-S.): a, nymph; b, 
Enlarged about three times. {From U. S. D. A. Farm. Bull. 890.) 



adult. 



are easily located and knocked off into dishes containing kerosene. In 
fall and spring they are attracted to baits, either of cottonseed or sugar 
cane, where they can be killed with kerosene. The bugs also feed and 
breed freely on Hibiscus and the Spanish. Cocklebur, and the destruction 
of these plants near cotton fields will prevent their breeding there and 
spreading in larger numbers to the cotton. 

Family Lygaeidae. — There are many kinds of insects in this family 
but nearly all are small, being in most cases less than a third of an inch 
long. A number occasionally injure various plants, and one — the 
Chinch Bug — is one of the worst half-dozen pests in the United States. 

The Chinch Bug (Blissus leucopterus Say). — This little bug, less than 
a quarter of an inch long, feeds on all the grasses and cereal crops. It is 
apparently a native of tropical America which has migrated northward, 



THE HEMIPTERA 



175 



up the Atlantic Coast, the Mississippi Valley and the Pacific Coast, and 
is now found everywhere south of the St. Lawrence River and the Great 
Lakes and also in southern Ontario, Minnesota, Manitoba, the Dakotas 
and along the eastern slope of the Rocky Mountains to Texas. It has 
also been found in Arizona, California and Washington. It is not a 
serious pest usually in the northeastern states and many of the others, 
but in the Mississippi Valley it often destroys crops valued at a hundred 
million dollars, in one season. 

The adult bug (Fig. 166) is a tiny insect seemingly incapable of causing 
so much injury, but its enormous numbers make up for its small size. 




a b c 

Fig. 166. — Different stages of the Chinch Bug {Blissus leucoptcrus Say): a, nymph 
in first instar; b, fourth instar nymph; c, adult. All enlarged about nine times. {Modified 
from III. Agr. Exp. Sta. Bull. 95.) 



Its body is black or dark gray, with white and therefore conspicuous 
wings, each having a single black spot. There are two forms of adult, 
however, one with long, full-sized wings; the other with short wings 
only partially covering the top of the abdomen. The former occurs in 
the Mississippi Valley while the latter is met with, together with the long- 
winged form, in the Atlantic States and to some extent inland from there 
along the more southern of the Great Lakes to Illinois. 

The long-winged form passes the winter as the adult in grass tufts, 
under fallen leaves or in other places giving it protection. Corn shocks 
left out over winter often harbor enormous numbers. In spring the bugs 
leave their winter quarters and fly to the grain fields. Here they lay 
their eggs, several hundred in number, on the ground at the base of the 
plants or on the roots just below the surface, this process lasting about a 
month. The average length of the egg stage is about 2 weeks and the 
young which hatch, suck the sap from the plants for about 40 days before 
becoming adult. The nymphs are yellow with an orange tinge about 
in the middle of the abdomen. This soon spreads over the greater part 



176 APPLIED ENTOMOLOGY 

of the body. In later stages the red becomes vermihon, with a pale band 
across the front of the abdomen, the head and prothorax dusky and 
before becoming adult the red becomes quite dark. 

Development, at least for the individuals coming from the later eggs, 
is not complete before harvesting time, and to finish their growth they 
are obliged to migrate and find more food. They accordingly march in 
armies, often travelling some little distance on foot, and many which 
have already become adults, able to fly, march with them. In new feeding 
grounds development is completed and the eggs for a second generation 
are laid. This generation appears to feed more particularly on corn, 
kafir corn, millet and other, similar crops, and its members become 
adult before winter, and go into hiding until the following spring. 

With the short-winged form, hibernation at a distance from its food 
plant is impossible because of its inability to fly. This form therefore 
winters in grass-land and begins its work there in the spring. It is a 
question whether there is more than one generation a year for this form. 
Migrations when they occur, are of course on foot, and corn is no more 
lia})le to be attacked than timothy or any other grass crop. 

The Chinch Bug is particularly affected by weather conditions, 
dry weather being favorable, and wet seasons unfavorable. Dry weather 
appears to induce migration, and a succession of several dry years 
favors a large increase in their numbers and consequently of the injury 
they cause. Rains during the hatching periods of the eggs are very 
destructive to the insect, and the suppression of a Chinch Bug attack, 
anticipated because of the great abundance of the wintering bugs, by 
heavy rains at the right time in the spring is one reason why these pests 
are not even more serious than is the case. 

A fungus (Sporotrichum glohuliferuni Speg.) generally called the 
"Chinch-bug Fungus" frequently attacks this insect, particularly during 
periods of wet, cool, cloudy weather, and then kills enormous numbers 
of them. In dry seasons it seems to have little effect, and attempts 
to control the Chinch Bug by placing individuals inoculated with the 
fungus in infested fields, while successful from the experimental stand- 
point, have on the whole, hardly produced the results hoped for. It 
is most valuable in seasons which are dry during the egg-hatching period 
but wet thereafter. 

In seasons then, when rains occur during the egg-hatching periods 
of the bugs, these and the fungus present will usually prevent serious 
outbreaks. In dry seasons, and particularly where there are several in 
succession, artificial methods of control must be resorted to. 

Control. — Numerous methods of control have been tested, with vary- 
ing degrees of success. Destruction of the adult bugs while wintering, 
has proved to be an efficient treatment when conditions are such as to 
make it reasonably complete. Burning over fields where the bugs are 



THE HEMIPTERA 177 

hidden in the grass has destroyed from about 50 to 75 per cent of them 
in cases where counts of the bugs could be made, including as well, how- 
ever, areas covered with weeds, fallen leaves and other rubbish. The 
difficulty with this treatment is to get weather conditions such that the 
burning can be well done and without injury to the grass. Where 
thickets, hedges and other excellent hibernating places which cannot be 
burned out are plenty, this treatment, while of value for the bugs in the 
areas where this method can be used, will of course fail to reach those in 
the other locations and thus leave many to appear in the spring. 

Where Chinch Bugs leave one field for another, an old practice 
has been to plow a furrow across their line of march and dig an occasional 
hole in the furrow into which the bugs, diverted from their first direction 
of march, might fall and be destroyed with oil or other material. Bands 
of tar or of road oil across their line of march have also been used with 
some success, the difficulty with this plan being in most cases that the 
band must be placed on firm, hard ground or it will soak in and need 
frequent renewal, besides forming (with some materials) a surface film 
on which the bugs can cross. 

Crude creosote similarly applied, has recently been found to work 
well. Though it soaks into the ground it appears to repel by its odor, 
and the bugs reaching the band turn away from it. Renewal is necessary 
only when the odor becomes so slight that it no longer acts as a repellent. 
In 1914 the average cost for material of maintaining a mile of this band 
during the migrating period of the bugs was only $16.50 at the then 
prevailing price of the creosote. 

When the Chinch Bugs are entering fields (usually corn) at this 
season, spraying the plants with kerosene emulsion. Nicotine sulfate 
40 per cent and soap solutions has been tested. The former is liable 
to injure the plants if great care is not given to its application, but the 
tobacco extracts have proved satisfactory. Soap alone, used at the 
rate of 3 oz. per gallon of water has given excellent results, and while 
the Nicotine sulfate, using ^^ fl. oz. in 1 gal. of water in which }4 oz. 
of soap has been dissolved, may be the most effective, soap alone is 
likely to prove very satisfactory and is less costly. As the bugs enter 
corn fields from elsewhere, the spray need be applied only to the outer 
rows if the invasion is observed in time. 

The advice has also been given to cease planting corn in years 
when the Chinch Bugs are liable to be abundant, raising instead 
cowpeas, buckwheat, stock beets or soy beans, on which the bugs do 
not feed. 

In the case of the short-winged form there is little migration, and 
plowing and the rotation of crops where the insects appear, seems to be 
about the only treatment available, and probably all that will 
be necessary. 

12 



178 APPLIED ENTOMOLOGY 

That insects like other animals suffer from the attacks of various 
diseases, is perhaps not generally realized. Yet the hst of these diseases 
is not a small one and our knowledge of them is still extremely limited. 
Some of them are caused by bacteria and are just as truly germ diseases 
as are those from which man suffers. Others are caused by parasitic 
plants which in one way or another enter the body of the insect and grow, 
consuming the nourishment they find there and finally kill the animal, 
usually making its body hard and firm, or "mummifying" it. A third 
type of disease is that known as the "wilt disease," in which neither 
bacteria nor fungi have been discovered, where the insect "wilts" after a 
time, becomes soft, and gradually decays. The producing cause of this 
class of diseases is still unknown, but they are infectious, spreading from 
one individual to another, and where the insects are abundant and 
weather conditions are favorable they cause a high mortality. 

Attempts have been made to utilize diseases for the control of insect 
pests. The Chinch Bug has been the subject of one of the most thorough 
of these experiments, the fungus already referred to having been cul- 
tivated for the purpose. It was found that by the use of appropriate 
methods, cultures of the fungus obtained in the fall could be grown 
during the winter, and bugs inoculated with it in the spring could be sent 
out to fields where the insects were abundant, and liberated there to 
spread the disease. To some extent this was a success, but it was soon 
found that if the inoculated bugs were set free during dry weather the 
disease failed to spread rapidly enough to prevent great injury, while if 
the weather was wet the fungus was in most cases already present and 
the addition of more diseased bugs at best only hastened its spread 
somewhat. As a business proposition then, the artificial cultivation 
and distribution of the fungus has been given up. 

In the case of a bacterial disease of grasshoppers which has at times 
been observed greatly to reduce the numbers of this insect, somewhat 
similar results have been obtained. In a few instances some degree 
of success has been secured by spreading the germs, but here the factor 
of cannibalism seems to enter into the problem. With species of grass- 
hoppers which feed considerably on dead or dying individuals, there is 
some probability of successful treatment in this way, but such species 
are not numerous, and there also appears to be more or less immunity 
to the germ in some species. 

The whole ptoblem of control by disease appears to hinge on satis- 
factory answers to three questions: Can the disease be cultivated so 
that a supply can be obtained and continued? Can it be introduced 
successfully into regions where it is needed but not present? Will the 
disease establish itself there and become effective? 

The answers to the first two of these questions are liable to be affirma- 
tive ones, though this is not always the case. The third is the most 



THE HEMIPTERA 



179 



difficult to determine. It may be that the disease is not already present 
where it is desired to introduce it because conditions there are such that 
it will not thrive. Fungous diseases at least are influenced to a very 
large degree by the weather, most of them thriving best in warm, moist 
weather and if these conditions are not present they will amount to little. 
At the present time it would appear that the success of artificially 
introducing diseases to control insect attacks is so dependent upon 
weather conditions that man can do little more than supply the disease 
and trust that the needed kind of weather may follow. Unfortunately 
the very conditions under which injurious abundance of the insect take^ 
place, appears in too many instances to be those distinctly unfavorable 
to the spread of the disease. 

Family Tingididae. — The insects (Fig. 167) of this family are delicate 
little bugs, usually having the pronotum broadly expanded and, with the 




Fig. 167, 



-Example of a Tingidid Bug (Gargaphia solani Heid.), enlarged about ton tinief 
{From U. S. D. A. Farm. Bull. 856.) 



hemielytra, covered with reticulated marks, giving them something the 
appearance of a bit of lace and this has been responsible for their com- 
mon name — lace-bugs. They are rarely more than an eighth of an inch 
long, usually whitish in color, and suck the sap from various plants, 
being generally found on the under side of the leaves. Their eggs are 
placed on the leaves, generally at the tops of small, brown, rather conical 
projections produced by the bugs, and which somewhat resemble places 



180 



APPLIED ENTOMOLOGY 



where fungi project from the leaf surface. Several species are occasion- 
ally rather injurious. 

Family Miridse. — This family until recently was called the Capsidae. 
It contains a very large number of species, perhaps more than any other 
family of bugs, all small, and all feeding on plant juices. Some feed on 
grass; others on succulent stems; some make a specialty, at least at cer- 
tain seasons, of sucking the sap from leaf and flower buds, distorting 
them or even preventing their development. Sometimes they are 
present in great numbers and do much injury. Fruit is attacked by some 
species, while it is small and rapidly growing, and such attacks produce 
"dimples" or small depressed areas, or they may even deform and thus 
greatly reduce the value of the fruit. Many secondary and potential 
pests belong in this family. 

Some of the adults are bright red; others red and black, yellow and 
black or other colors. In those feeding on grass, grayish-yellow or 
greenish-yellow is a frequent color. In many cases 
it seems that this is in some way connected with the 
color of their food, as for example, some species 
found on the stems of the red dogwood are them- 
selves largely red, though in other cases it is difficult 
to discover any such correspondence of color between 
the insect and its food plant. 

The Meadow Plant-bug {Miris dolobratus L.). — 
This is apparently a species introduced from Europe 
about a hundred years ago and now found over the 
eastern United States and as far west and south as 
Minnesota and Kentucky. It attacks cultivated 
grasses and is often extremely abundant. The adult 
(Fig. 168) is a rather slender bug about two-fifths 
of an inch long, with quite narrow wings. It is 
gray or yellowish-gray with darker markings and has long, black 
antennae. 

The eggs are laid in late summer and fall in grass stems, for the most 
part below the cutting level. They hatch the following spring and 
the nymphs feed on the sap of the plant stems for a little over a month 
before becoming adult. Many of the adults have short wings, a similar 
condition to th^t found in the chinch bug, but here the two forms mingle 
everywhere, though the short- winged individuals may make up as much 
as 90 per cent of the total number. 

Control. — Wintering in the egg stage in grass stems suggests the 
possibility of destroying many of the insects by burning over grass fields 
and particularly places where the grass was not cut, during the winter 
season. Early and close cutting of the fields might leave the insects 
little to feed on. Fall pasturing of the fields and the cultivation of sod 




Fig. 168. — Meadow 
Plant-bug (Miris 
dolobratus L.), nearly 
twice natural size. 
{Original.) 




THE HEMIPTERA 181 

land found heavily infested may be of assistance, but so far, little or 
nothing has been done to combat this pest. 

The Tarnished Plant-bug {Lygus pratensis L.). — The Tarnished Plant- 
bug is widely distributed, both in Europe and this country. It is about 
a quarter of an inch long (Fig. 169), shorter and broader in proportion than 
the Meadow Plant-bug, and varies greatly in its coloration. The general 
color, however, is brown, variegated with shades of yellowish and brown- 
ish and with black spots in some places. 

This pest feeds on over 50 different kinds of plants which are 
of value to man. The adults attack apple, pear, peach, and in fact all 
fruit tree buds, destroying or at least 
seriously injuring them: small fruits 
are often stunted or "buttoned" by 
them: flower buds of such plants as 
the chrysanthemum, dahlia, peony 
and aster are punctured and de- 
stroyed or malformed: potato leaves 
are often injured, causing tip-burn, 
and beets, particularly sugar beets, 
have their leaves curled and injured. 

^ 1 i i 1 ji ■ Fig. 169. — Tarnished PI a at- bug 

Corn, wheat, oats and other gram (Lygus pratensis h.)-. a, adult- b, nearly 

and grass crops are also injured by full-grown nymph. Nearly four times 

... . (-1 -iTT-ii natural size. {From U. S. D. A. Farm. 

this omnivorous feeder. With young ^^^u ggg -, 

peach trees in nurseries it causes the 

trouble called "stop-back" by killing the terminal buds, and it is a 

carrier of the fire-blight of the pear, conveying the bacteria causing this 

disease from infected to healthy trees. It is therefore a serious pest. 

The insect passes the winter as the adult and possibly as the nearly 
full-grown nymph also, in protected places, and appears with the first 
warm spring days and attacks the buds of fruit trees and other plants. 
Its eggs are inserted in leaf veins and stems, flowers and similar places, 
and they hatch in about 10 days. The nymphs feed on the juices of the 
plants and become adult in from 3 weeks to a month. There is therefore, 
time for several generations in a season, though the actual number of these 
does not appear to have been worked out and probably varies somewhat 
according to the length of the season in different parts of the country. 

Control. — No effective method of control has as yet been discovered 
for this pest, though many have been tried. Spraying the plants infested, 
with kerosene emulsion, Nicotine sulfate or soaps, early in the morning 
has been found to kill some of them. Shields covered with sticky fly- 
paper, placed beside and over the plants which are then jarred, captures 
some: the destruction of all wild plants such as asters and goldenrod on 
which they feed and breed has been advocated ; and growing plants under 
cheese-cloth; driving the insects down the wind, and other methods have 
been suggested, but no really efficient control is yet known. 



182 



APPLIED ENTOMOLOGY 



Family Phymatidae. — The Ambush-bugs (Fig. 170) as members of 
this family ^re called are carnivorous bugs which usually hide in blossoms 
to capture insects visiting there. They are rather short and stout, 
generally less than half an inch long, and have colors so combined on their 
bodies as to render them very inconspicuous in the flowers. Their prey is 
generally any insect they can grasp with their stout fore legs, whether 
it be injurious or otherwise. 





Fig. 170. Fig. 171. 

Fig. 170. — Ambush-bug {Phytnata erosa icolffii Stal.): a, from above; h, from the side, 
showing the grasping front leg. Enlarged: true length shown by hair line. {Modified 
from Sanderson and Jackson, Elementary Entomology, after Riley, U. S. D. A.) 

Fig. 171. — Reduviid Bug, about natural size. (Original.) 

Family Reduviidae. — This large family consists of carnivorous insects 
some of which are small while others are considerably more than an inch 
long (Fig. 171). Though generally feeding on the blood of other insects 
they may occasionally attack man and in such cases produce rather 
painful wounds. One species, most common in the Southern States, 
often enters houses and feeds upon the bedbug, and from this habit has 
been called the Masked Bedbug Hunter, the mask referring to dust which 
adheres to its rather sticky body before it becomes adult. Another 
species in the West and South is occasionally found in beds where it 
imitates the habits of the true bedbug. A similar but different species 
occurs in California. 

The group as a whole, preying as its members do upon other insects 
almost entirely, must be regarded as a beneficial one. The family is 
most abundant in the warmer climates. 

Family Cimicidse. — The Cimicidse is a very small group but well 
known through one of its members, the Bedbug. All of the insects 
belonging here are small, rather oval in outline, very fiat, and rather 
reddish in color. Birds, poultry and bats are attacked by species similar 
to but smaller than the Bedbug and some of these under unusual condi- 
tions, may enter houses and attack man. 

The Bedbug {Cimex lectularius L.). — ^This universally distributed 
and well-known pest (Fig. 172) appears to have originated in Asia and 
has now spread wherever man is found. It is a small, flat insect, reddish- 
brown in color, about a fifth of an inch long when adult, and wingless, 



THE HEMIPTERA 



183 




only tiny stubs of wings remaining to show that it has been derived 
from winged ancestors. It produces a very noticeable odor. 

It is a nocturnal animal, hiding during the day in any cracks and 
crevices it may find, either in the bedstead, behind loose wall paper or 
elsewhere. In these places it lays its eggs, probably about 200 in num- 
ber, these hatching in from a week to a much longer period dependent 
upon the temperature. The nymphs are yellowish-white at first, turning 
brown gradually with increasing age. Nymphal life varies greatly in its 
length, being affected by the temperature 
and food supply, but when these are favor- 
able, about 7 weeks is required to produce the 
adult bug. Under less favoring circumstances 
the nymphs may remain unchanged but alive, 
for a long period. The number of genera- 
tions in a year may therefore differ greatly 
under different conditions but in warmed 
houses there are probably at least four. 

Where human blood is not obtainable for 
food, that of mice, rats or other animals 
where available, may be taken instead, and 
living bedbugs in empty houses may perhaps 
be accounted for in this way. Without food, 
however, death within a year is a practical 
certainty. 

The "bite" of the bedbug is quite poison- 
ous to some persons but not to others and in 

some cases a sort of immunity is obtained by individuals continuously 
exposed to attacks. 

Bedbugs are known to be carriers of contagious diseases of man, such 
as the African relapsing fever, Kala-azar, plague, and possibly leprosy 
also, but of course the insect must first become itself infected with the 
causal agent of the disease which is very rarely the case, at least in 
the United States. It does not appear to transmit the diseases except 
as the agents of them by accident get on the mouth parts of the insect. 

Control. — Where sulfur can be burned in a room, using a pound for 
each 1,000 cu. ft. of space for 24 hr. the fumes will destroy all stages of the 
bedbug if the room is reasonably tight. A thorough treatment of all places 
where the insects can hide and lay their eggs, with gasoline, benzine or 
kerosene is also successful if the material penetrates all parts of the cracks. 
Corrosive sublimate at least as strong as a 6 per cent water solution, can 
be used in the same way. Heating a room or house to from 120 to 130°F. 
in summer for an hour or even less has proved effective, as has a tempera- 
ture below 32°F. continued for 3 or 4 weeks. Persons obliged to stop at 
infested places can usually obtain protection by (kisting insect powder 
[Pyrethrum) between the sheets of the bed. 



Fig. 172 .—Adult female 
Bedbug (Cimex lectularius L.) 
gorged with blood. Greiitly 
enlarged. {From V. S. D. A. 
Farm. Bull. 754.) 



184 



APPLIED ENTOMOLOGY 



Family Gerridae. — These insects, the Water Skaters or Water Striders 
(Fig. 173) as they are commonly called, are often noticed during the 
summer, skating over the surface of quiet pools of water. Their bodies 
are slender in most cases, less than half an inch long, usually black or 
brown, and their long, slender legs project some distance from the body. 
A few are shorter and broader bodied. They feed on any small insects 
they are able to capture and winter 
either under sticks or stones under 
water, or in mud near the edge, under 
leaves and rubbish. A few live on 
the surface of the ocean in warm 
climates. They are interesting insects 
to watch but are of little if any 
economic importance. 

Family Notonectidae. — The Back- 
swimmers (Fig, 174) as they are 
termed, live in fresh water. They 





Fig. 173. Fig. 174. 

Fig. 173. — Water Skater (Gerris conformis Uhl.) about natural size. {Original.) 
Fig. 174. — Notonectids and Corixid: A, Notonectid at the surface of the water 

showing under surface; A', swimming showing upper surface; B, Corixid swimming. 

Somewhat enlarged. {From Linville and Kelly, Text-book in General Zoology.) 

are small, rarely more than half an inch in length and generally black 
and cream-colored. The back has sloping sides something like the 
bottom of a boat and they swim on their backs, propelling themselves 
by their long legs which are fringed with hairs. They occasionally 
come to the surface for air, a supply of which they carry down with 
them under their wings and between the fine hairs covering the under 
side of the body. They are carnivorous, feeding on other small insects 
but are of little importance. 

Family Corixid ae. — Living in the same places and with similar habits 
to the Back-swimmers are small, greenish and blackish mottled insects, 
rather oval in outline with heads somewhat flattened in front, and known 
as Water-boatmen (Fig. 174J5). They have long, fringed, oar-hke legs 
but do not swim on their backs and in some way are able to remain under 
water without coming up for air for a much longer time than the back- 



THE HEMIPTERA 



185 



swimmers. Like the latter group they often leave the water and fly at 
night and are frequently attracted to lights. 

Family Nepidae. — The water-scorpions as these insects are called, 
live in fresh-water ponds and pools. Two types of form are included, 





Fig. 175 



Fig. 176. 



Fig. 175. — Water-scorpion {Ranatra americana Montd.) about natural size. (Original.) 
Fig. 176. — Giant Water-bug (Lethocerus americanus Leidy), natural size. {Original.) 

one having a long, slender body and long legs (Fig. 175), the front pair of 

which, unusually long, are constructed for grasping their prey which 

consists of small insects. In the other type the body is short, rather broad, 

and flat. In both a long tube consisting of two pieces which can be pressed 

together to form the tube, joins the hinder end of the 

body and while the insect is an inch under water in 

some cases, this tube is pointed upward until its tip 

is out of water and through it the insect obtains air. 

The slender forms lying quiet on the bottom of pools 

resemble dead twigs and thus obtain the concealment 

needed to enable them to get within reach of their 

food. 

Family Belostomidas, — These insects are gen- 
erally termed the giant water-bugs. Some of them 
are the largest members of the Hemiptera, being 
two, three or more inches long, broad, flat and brown 
in color (Fig. 176). They live in fresh water and 
feed on insects and even small fish and are thus 
sometimes injurious in the production of food fishes. They fly by 
night and are frequently attracted to electric lights, which has led to 
the larger species being sometimes called "electric-light bugs." In some 
of the smaller species (Fig. 177) the eggs are laid on the back of the male 
who is thus obliged to 'carry them around until they hatch. 




Fig. 177. — Male 
Belostomid (Belostoma 
fiumineum Say) carry- 
ing eggs on its back. 
Natural size. {Orig- 
inal.) 



CHAPTER XXVI 
THE HOMOPTERA 

The Homoptera is a large group containing insects of many forms, 
often showing httle resemblance to one another. They suck sap from 
plants through a beak, apparently very similar in structure to that al- 
ready described for the Hemiptera, but it is attached, not to the front but 
to the hinder part of the under surface of the head which is very closely 
joined to the prothorax so that the beak frequently appears to arise 
between the front legs. In some instances where the adults do not feed, 
this structure is lacking. The wings are often absent but when present 
are usually held, while at rest, sloping over the body Hke a house roof. 
They are of the same thickness and usually, though not always, trans- 
parent. In this group (except the male scale insects) the metamorphosis 
is incomplete. These facts may be summarized as follows: 

The Homoptera are suckmg insects with the beak {when present) arising 
from the hack part of the under side of the head which is very closely joined 
to the prothorax. The wings {frequently absent) are of uniform thickness 
throughout and when not in use are held sloping over the body. The meta- 
morphosis {except in male scale insects) is incomplete. 

Few groups of insects show as great differences in their members as are 
found here. The cicadas, often two or three inches in length and with a 
wing spread of four inches or more, are among the giants of the order, 
while some of the white flies and scale insects are hardly more than 
just visible to the eye. Most of the group move about freely, though 
some locate in one place soon after they hatch and remain there 
the rest of their lives. In one section the insect produces a protec- 
tive scale which covers it, and beneath this, degeneration of some 
parts of the body occurs. 

Many Homoptera secrete a sweet, sticky fluid called honey-dew, 
often in such quantities when the insects are in abundance, that in falling 
it makes a noise like fine rain. Striking on leaves, fruit or bark, it adheres 
and dries, and a blackish fungus grows in it, giving to such places a sooty 
appearance. This secretion appears to be produced most abundantly by 
the soft scales, white flies, plant hce, jumping plant Hce and some of 
the tree hoppers. Ants and honey bees feed on the honey-dew and 
frequently visit the insects producing it, for this food. 

Nine families of Homoptera are generally recognized, but four of 

186 



THE HOMOPTERA 



187 



these may, for convenience, be combined here. The six to be considered 
therefore are: 

Cicadas (Cicadidae). 

Leaf Hoppers and Tree Hoppers (four families). 

Jumping Plant Lice (Chermida?). 

Plant Lice (Aphididae). 

White Flies (Aleyrodidse). 

Scale Lisects (Coccidae). 



Order Homoptera < 



Family Cicadidae (The Cicadas) . — Most of the members of this family 
are rather large insects, with bodies often two or three inches or even 
more in length and quite stout as well. Their wings are correspondingly 
large, and in some species have a spread of more than six inches. Though 
usually transparent and with prominent veins they sometimes have 
pigmented areas of various colors. 

The adults place their eggs in slits they make with their ovipositors 
in twigs. On hatching the nymphs drop to the ground and make their 
way to the roots where they feed on the sap. Metamorphosis is more 
nearly a complete one than in the other families of Homoptera (except 
the scales), the nymph having but little resemblance to the adult, and the 
last two nymphal stages are rather transitional in appearance between the 
two. 

The adult males have vocal organs located on the under side of the 
basal segments of the abdomen and covered by extensions backward of 
the metathorax. The sound produced is often so loud, especially when 
the insects are abundant, as to be very noticeable and eve a unpleasant. 
No auditory organ has as yet been discovered with certainty, in either 
sex. 

Cicadas are particularly inhabitants of warm countries, though some 
species are abundant quite far from these regions. In North America 
they occur in Canada and probably in 
all the States farther south, and are 
found as far north as England in the 
Old World. They are often wrongly 
called locusts. 

The Periodical Cicada or Seventeen- 
year Locust {Tihicina septendecim Say). 
— This remarkable insect is a native of 
North America. It is found from Mass- 
achusetts to Northern Florida and west 
to Wisconsin, Iowa, Kansas, Oklahoma 
and Texas, but is much less important near its northern limits than near 
the center of its range. 

The adult (Fig. 178) is about an inch long, with a stout, black body, 
orange eyes, legs and wing veins. The wings when at rest extend consid- 




FiG. 178.— Adult Periodical Cicada 
{Tihicina septendecim Ij.) , natural size. 
{Original.) 



188 APPLIED ENTOMOLOGY 

erably behind the body. In the far South it appears early in May while 
near its northern limits it may be as late as early June. The insects are 
usually in evidence for 5 or 6 weeks and are particularly noticeable in and 
near wooded areas. They suck the sap from various trees but do little 
injury in this way. The females lay their eggs in the smaller twigs of 
trees, shrubs and even in herbaceous plants, the oak and hickory, and in 
the case of fruit trees the apple seeming to be preferred for this purpose, 
though more than 75 kinds are attacked. The eggs are placed in slits 
made in rows by the ovipositor and a twig thus punctured is liable to 
break off either entirely or in part. The eggs hatch in 6 or 7 weeks and 
the nymphs drop to the ground and burrow to the roots where they feed 
until the seventeenth spring from the one when they entered the ground, 
most of them being between six and eighteen inches below the surface. 

During the seventeenth spring the nymphs burrow upward, nearly to 
the surface of the ground but do not usually come out until ready for the 
final molt producing the adult. In some cases, however, upon reaching 
the surface they construct earthen cones or chimneys sometimes six or eight 
inches high, within which the burrow is continued. It is supposed that 
these are constructed where the cicadas are in moist places and these 
structures will bring the insects out above the moisture, or that a shallow 
soil enables them to reach the surface before the normal time, or unusu- 
ally warm conditions hasten their start, and on their arrival they are 
not ready for their final molt. Recent work indicates that length of 
day is a factor. Probably the last word on this subject has not yet 
been said. 

Arrived at the surface of the ground and ready to molt for the last 
time the nymphs crawl out of their burrows, the greater number of them 
in the afternoon and evening, and make their way to any objects such as 
a tree, stick or anything at hand, and on these molt for the last time and 
become the adults which are ready for flight the next morning. 

In the course of nearly 17 years of underground feeding it is only natu- 
ral that some finding an abundant food supply should be able to gain a 
little time and appear during the sixteenth year as "forerunners" of the 
main brood, and that others with scanty food should be delayed until the 
eighteenth season. These are few in number, however. In the South 
is a race with a 13-year life, the origin of which as related to the other 
race is not as yet explained. 

Though a cicada's life is (except for the race just mentioned) 17 
years, they occur in one place or another every year, showing that in 
some way in the past these insects have diverged so that there are now 
17 broods. Some places are so unfortunate as to have several of these 
broods but though the cicada may appear there every 4 or 5 years, the 
descendants of any one of these will not be found until 17 years have 
elapsed. 



THE HOMOPTERA 189 

Some of the broods are more abundant and widely distributed than 
others. Four are of sufficient importance to be mentioned. These are 
Brood II, due in 1928 from Connecticut into North Carolina and at a few 
scattered points to the west; the insects are quite abundant: Brood VI, 
due in 1933, widely scattered over the country but not very abundant: 
Brood X, due in 1936 from New York to Georgia and west to Michigan 
and Illinois and at scattered points elsewhere, this being the most abun- 
dant brood: and Brood XIV, due in 1923, from Massachusetts to Georgia 
and west to Illinois; also an abundant brood. The important thirteen- 
year broods are: XIX, due in 1924, from Iowa to Louisiana and eastward 
to the Carolinas and Virginia, the largest of these broods : and Brood XXIII, 
due 1928, from Missouri, Illinois and Indiana down the Mississippi Valley 
with scattered colonies here and there to the east as far as Georgia. 
This is also a large brood. 

Numerous enemies of the Periodical Cicada are known, many of them 
being parasites. Some birds feed on them and a fungus causes disease 
of the adults. Various mammals feed on them as they are coming out of 
the ground. 

Control. — In forests nothing can be done to control these insects, 
but when they appear in sufficient numbers in parks and orchards to 
make treatment desirable, certain methods for preventing injury or for 
the destruction of the insects are feasible. In some cases collection 
of the adults by hand has paid. In others, spraying the tree-trunks 
and other objects on which they rest while molting after leaving the 
ground, aiming to hit as many of the insects as possible, and using a 
strong kerosene emulsion for the spray material has proved quite effec- 
tive, for where the cicadas are not killed they are crippled by the action of 
the particles of the spray which strike them. This treatment, however, to 
be successful must be repeated every evening about sunset or verj'- early 
in the morning before the insects begin to fly, as long as they continue 
to come out of the ground. 

In the case of fruit trees anywhere, pruning is not advisable the spring 
cicadas are due in that locality, until after the eggs are laid. Then, 
pruning and burning the punctured twigs before the eggs hatch is desirable. 
In some cases young trees suffer so severely that it is not advisable to 
set out nursery stock the year before cicadas are due. Apple "whips" 
however, can usually be safely planted the same spring that the cicadas 
come, being generally too small to suffer much by the attacks of these 
insects. Hogs allowed to run under trees known to have cicadas at 
their roots will kill many of these pests as they come to the surface to 
become adult in May and June of their seventeenth year. 

Various species of cicadas are common in nearly all parts of the United 
States. In the East the Dog-day Harvest-flies {Tibicen linnet Sm. & 
Grsb., and others) are often noticeable (Fig. 179), singing in the trees 



190 



APPLIED ENTOMOLOGY 



during late July and August. Most of these species are somewhat larger 
than the Periodical Cicada and generally black and olive-green, with a 
white powder or "bloom" on the under side of the body. They are 
supposed to have about a 2-year life history and 'as individuals occur 
every year, two distinct broods. A few of these species greatly resemble 
the Seventeen-year Cicada in color but are smaller, and as they appear 
more than a month after the latter have disappeared, no confusion should 
lead to the belief that the Seventeen-year Cicada has appeared at that 
season. 







<f^vs3 


.■rif^f''':\^: j;fyw 




" ;5^:>?..il 






Fig. 179. Fig. 180. 

Fig. 179. — Adult Dog-day Cicada {Tibicen linnei Sm. and Grsb.), natural size. 
(Original.) 

Fig. 180. — Tree-hoppers showing remarkable forms of the pronotum. Enlarged 
about twice. (Original.) 



Leafhoppers and Treehoppers. — The four or more families included 
under this heading contain a large number of kinds of insects, many of 
which are extremely numerous. Among them are the lantern-flies of South 
America and the candle-flies of China and India which are quite large insects, 
a number of which at least are luminous. Some of the insects here in- 
cluded are highly colored and some secrete quantities of wax which is often 
used for candles and other purposes. 

In one of the families — the Treehoppers — the pronotum is largely and often 
remarkably developed, sometimes giving these insects a very grotesque appear- 
ance. In this country, however, such forms are not usual, the development of 
this section of the body being mainly in the line of horns or humps and the 
enlargement of this plate in width or height and in its extension backward until it 
covers most or all of the body (Fig. 180). The Treehoppers of the United States 
are all small insects, less than half an inch long, and as they sit on twigs their 
peculiar forms seem to give them resemblances to buds, swellings or other charac- 
ters, which suggests that their odd outlines may be for resemblance to these 
structures and thus secure the protection from their enemies which this would 
give. 

In general the Treehoppers puncture the twigs of plants and are injurious, 
though only a few kinds are ever so abundant and attack plants of such impor- 
tance as to need consideration. 

Among these the most common is the Buffalo Treehopper (Ceresa bubalus 
Fab., Fig. 181) found practically everywhere in the United States except perhaps 



THE HOMOFTERA 



191 




Fig. 181.— Adult 
Buffalo Tree-hopper; 
view from above. 
Enlarged about 
twice. (Original.) 

Most 



in the most southerly portions, which injures the twigs of fruit trees by its egg 
punctures made in the fall. Two rows of punctures are made, nearly parallel to 
each other, the two rather resembling parenthesis marks, 
and in each a number of eggs is laid which hatch the follow- 
ing spring. Injury caused by the feeding of the nymphs and 
adults is slight, and in fact most of the young feed mainly 
on weeds, but the egg punctures (Fig. 182) cause distorted 
growth and weaken the twig. Spraying with a fairly strong 
contact insecticide to destroy the nymphs wherever these 
are found, and the destruction of all weeds like burdock, 
thistles, etc., near the fruit trees appear to be the only 
methods of control, and the former is rarely practicable. 

The Leafhoppers (Fig. 183) are extremely abun- 
dant insects and some of them must do much injury 
to the grass crop as it has been estimated that there 
are frequently as many as one to two millions of them per acre 
of them are very small. 

Some leafhoppers have one generation a year, others more, and 

different species appear to hibernate in 
different stages. In addition to various 
grasses, grain, alfalfa, clover, sugar beets, 
grape, and rose, the apple, elm, willow 
and other trees have their juices ex- 
tracted by the feeding of these insects. 

A group of tiny leafhoppers known as 
froghoppers or spittle insects (See Fig. 183) 
is also included here. They are common on 
grasses and other herbaceous plants and also 
on some trees such as the pine, etc. The 
nymphs produce a fluid and Hberate air in 
a sort of froth or "spittle" in which they 
in the northern states practically across 




Fig. 183. — Three kinds of Leaf- 
hoppers enlarged about twice. The 
left hand figure is of a "spittle in- 
sect." {Original.) 



way 
are very 



as to form 
abundant 



this in such 
live. They 

the entire continent, and one species, the Grass-feeding Froghopper 
(Philcemis Kneatiis L.) is often so common as to wet the shoes of a person who 
walks through the grass in June. The nymphs suck the sap from the grass stems, 
withering and turning white the upper parts of the stems and the blossoms, much 
as does the grass thrips. Burning over old grass fields where these insects are 
most abundant, in early spring wiU destroy many of these insects in their winter 
quarters close to the ground. 

The Apple Leafhoppers (Empoasca mali Le B. and others), tiny insects 
about a twelfth of an inch long, attack over fifty different kinds of 
plants being generally most abundant on the apple, Norway maple, 
and some kinds of oaks among the list of trees, and on alfalfa, clover, 
potato and beets. They appear to occur in almost every part of the 
United States and in some sections of Canada. The adults are 
generally pale green with white markings on the pronotum. Other 
similar insects are often present along with these species, but treatment 
for all would be identical. 



192 



APPLIED ENTOMOLOGY 



The apple leafhoppers winter as the adults under rubbish and In spring 
after mating the eggs are laid in the veins of the leaves. Some observers 
claim that at least a part of the nymphs in spring hatch from eggs laid 
in apple bark in the fall. The eggs hatch in about a week and the nymphs 
feed for about 3 weeks, and the adults of these nymphs lay eggs for 
another generation. In the middle Atlantic States there are three 
generations each year, but this number may be reduced near the northern 
limits of their range or increased farther south. 




Fig. 182. — Twigs showing injuries caused by the Buffalo Tree-hopper in laying its eggs. 
About natural size. {From Brilton, Fifteenth Rept. Conn. Agr. Exp. Sta. 1915.) 

The injury caused by these insects appears to be a curling and check- 
ing of the growth of the leaves in some cases, particularly those near the 
tips of the shoots in the case of young apple trees. Older trees suffer 
less than nursery stock. 

Control. — Spraying thoroughly with nicotine sulfate 40 per cent, 
1 part in 1,400 or 1,500 parts of water, with the addition of soap, is a 
successful treatment to use for these insects if applied soon after the 
nymphs appear in the spring, or at least before the leaves have curled. 
Good results have also been obtained by dipping nursery stock in a 



THE HOMOPTERA 193 

solution of whale-oil soap 1 lb. in 8 gal. of water, or dissolving a bar of 
common laundry soap in 6 to 8 gal. of water for the purpose. 

The Rose Leaf hopper {Empoa rosce L.). — This European insect is now 
present practically everywhere in the United States and is also found 
in Nova Scotia, Ontario and British Columbia. It is a general feeder 
and will probably attack most plants of the family Rosaceae, but appears 
to be particularly injurious to the rose and apple. The adult is almost 
as large as the apple leafhopper and is creamy white to light yellow. It 
lays its eggs during the fall in the bark of rose bushes, apple trees, berry 
canes and other plants and there they remain until spring, when they 
hatch. The nymphs suck the sap from the under side of the leaves of 
the plants, producing a mottled appearance, and as the injury increases 
the leaves may turn yellow and dry up, but they do not curl. There 
are two generations of this insect a year, the eggs for the second genera- 
tion being laid in July. Most of the wintering eggs are deposited in rose 
stems. 

Control. — This insect is rarely of importance as an apple pest but 
rose bushes often suffer by the loss of sap and the impossibility of their 
injured leaves performing their proper functions. Spraying infested 
plants with nicotine sulfate as for the apple leafhoppers, as soon as the 
nymphs are observed, is usually sufficient to prevent further injury. 

Many other leafhoppers are at times serious pests. The beet leaf- 
hopper in the Western States in addition to its injury to the plants by 
feeding, transmits a "curly leaf disease" and the grape leafhopper is 
sometimes so abundant that grape leaves in vineyards are turned brown 
and much injured. The six-spotted leafhopper attacks some grains and 
grasses, and other species generally of slight importance, at times assume 
prominence. In general, nicotine sulfate prepared as indicated above, 
is an effective control material for these insects wherever conditions 
permit its use. 

Family Chermidae. — The Jumping Plant-lice as the members of this family 
are usually called, are very small insects which feed on various plants but are 
rarely abundant enough to become of economic importance. One exception 
to this occurs and a consideration of that species will also give something of a 
general idea of the insects of the group as a whole. 

The Pear Psylla (Psyllia pyricola Forst.). — The Pear Psylla is a European 
pear pest which seems to have reached this country about 1832 and is now 
present everywhere in the eastern United States at least as far south as Virginia 
and west to the Mississippi River, and has also been reported (perhaps errone- 
ousljO from California. Where it is abundant it is very injurious, seriously 
checking the growth of the tree, so that many of the leaves turn yellow and drop 
off, as does much of the young fruit, while the entire vitality of the tree is reduced 
and it makes little or no growth. 

The adult (Fig. 184) is about a tenth of an inch long, the body black with 
reddish markings, and long antennse are present, E.xcept for this last feature 

13 



194 



APPLIED ENTOMOLOGY 



it greatly resembles a tiny cicada. The insects pass the winter as adults hiding 
in crevices of the bark or similar protected places and in spring lay their eggs 
on the twigs, and particularly around the bases of the buds. These eggs hatch 
in from 2 to 3 weeks according to the temperature. The nymphs (Fig. 
185) suck the sap from the axils of the leaves and fruit stems and if abundant 
gather around the bases of leaves and fruit stems and spread to the under surface 
of the leaves themselves. They move about but little and secrete large amounts 
of honey-dew, sometimes so much when they are very numerous, as to cover 
the leaves and branches. They are broadly oval, flat creatures, yellowish at 
first but blackish with reddish marks later and with bright red eyes. They 
become adult in about a month and lay their eggs, this time on the under side 
of the leaves or on the leaf petioles. These eggs hatch in a week to 10 days and 
adults are produced in about a month. There are three or four generations a 
year in New England and more in the South. 





Fig. 184. Fig. 185. 

Fig. 184. — Adult Pear Psylla (PsyUia pyricola Forst.) about ten times natural size. 
{Frojn Britton, Third Rept. Ent. Conn. Agr. Exp. Sta. 190.3, after Slingerland.) 

Fig. 185. — Nymph of Pear Psylla, greatly enlarged. {From Britton, Third Rept. Ent. 
Conn. Agr. Exp. Sta. 190.3, after Slingerland.) 

Control. — Methods for checking the injuries caused by these insects center 
around their control in winter and early spring. Most of the adults winter 
under the loose bark of the trees or in tufts of grass and rubbish near the trees. 
Scraping off all loose bark and removal of the rubbish, followed during any 
warm days in November or December by a thorough spraying of these places 
with nicotine sulfate, standard formula, will kill large numbers. It should not 
be cold enough for the spray to freeze on the trees. In spring, just as the clusters 
of blossom buds begin to separate from each other, but before the blossorns 
open, the lime-sulfur wash diluted at the rate of 1 part of the wash to 8 or 9 
parts of water will kill the eggs and any newly-hatched nymphs. The fruit 
spurs and the under sides of the twigs should receive particular attention with 
this treatment. 

Family Aphididse (Plant Lice or Aphids). — This is one of the most 
important groups of insects from an economic standpoint, as all its mem- 
bers are injurious, often very abundant, and a species usually doing little 
harm may at any time become a serious pest. 



THE HOMOPTERA 



195 



Aphids are tiny, soft bodied insects, the largest being less than a third 
of an inch long, generally with long legs and antennae, and are of various 
colors, green, black, various shades of red and brown, white and gray 
being the most usual ones. Some are more or less completely concealed 
(Fig. 186) beneath long, white waxy threads, giving them a "woolly" 







", '.4 

m 



Fio. 



186. — Alder twig covered by woolly plant lice, the "wool" entirely concealing their 
bodieik Somewhat enlarged. {Original.) 



appearance; others have a sort of dust or "bloom" like that on a plum, 
coating their bodies; but the majority (Fig. 187) are without any covering. 
Many species of aphids have a pair of tubes called cornicles, projecting 
upward from the top of the abdomen. These were formerly believed to 






^•1.^.", ^ 



.r>'^"..*^*^ 






Fig. 187. — Portion of leaf showing plant lice clustered together. 

(Original.) 



Somewhat enlarged. 



be the exit ducts through which honey dew, abundantly produced by the 
insects, escapes, but it is now known that this substance is expelled 
through the anus, often in such quantities that when the insects are abun- 
dant it forms a sort of fine rain which can be heard falling on the leaves 



196 APPLIED ENTOMOLOGY 

and ground. This fluid which is sweet and sticky is eagerly fed upon by 
ants. FalUng on twigs and leaves it dries there and a fungus grows in it 
turning it black, and plants where aphids have been abundant often show 
this by their black appearance. Some plant lice produce galls within 
which they live for at least a part of their lives but most of them are not 
thus enclosed, living on leaves, twigs, succulent plant stems or roots. 

Though there are great variations in the life histories of different 
aphids, certain general facts hold for most of the group. In general, eggs 
are laid in the fall, on a food plant of the species concerned, and these 
hatch the following spring. The nymphs soon become full-grown and are 
known as ''stem-mothers" and without fertilization (there are no males) 
produce eggs, or in most cases living young which like the stem-mother 
are all females and on reaching maturity produce young in a similar way. 
The production of young without fertilization of the parent is not uncom- 
mon in insects and is called parthenogenesis or agamic reproduction. In 
this case the production of these young alive rather than from deposited 
eggs introduces the additional fact that these insects are also viviparous 
except in (generally) one generation. The number of young produced by 
each parent varies but will perhaps average about ten, a few being born 
every few days, and the number of generations is variable but is also likely 
to be about 10, though the first born young in each generation, being a 
week or two older than the last born young, will gain enough time during 
the season to produce more generations than the others. In fact, in 
some species a range from 8 to 21 generations for late and early born 
individuals has been observed, and an average number of 28 young pro- 
duced per parent, so that the figures given above may be regarded as 
conservative. But even with this moderate estimate, allowing only 10 
young to a generation and 10 generations a season, the total product from 
a single egg hatching in the spring and itself counted as the first generation, 
would be 1,111,111,111, and this would be far below the actual number in 
most cases, were it not for the enormous destruction of these insects by 
their enemies and by unfavorable weather conditions. 

In many species instead of 10 young being produced per female as an 
average, the number is likely to be nearer a hundred, and in those species 
which also have more than 10 generations the total number of individuals 
which would theoretically be produced in a season "would be sufficient to 
completely cover the entire world with a continuous layer of plant 
lice." 

With such a marvelous reproductive power as this it becomes evident 
that despite natural checks to their increase, plants infested are liable 
after a few weeks to be entirely unable to provide food for the hordes of 
plant lice upon them. Accordingly we find that in most of the genera- 
tions winged individuals may be produced so that they can migrate to 
other plants. Winged and wingless forms may therefore be found at 



THE HOMOPTERA 197 

almost any time during the summer, and a wide distribution of the insect 
is obtained in this way. 

When cold weather approaches in the fall a generation appears, con- 
sisting of both sexes, and the females of this generation lay fertilized 
. eggs which winter over and hatch the following spring. In some cases 
this does not happen until the second fall and in a few species at least, 
sexual individuals have not been discovered and may occur only at long 
intervals, if at all. 

Many aphids do not feed entirely on one kind of plant but spend a 
part of the year on one species, and the rest on another. One of the 
species which is injurious to the apple remains on this tree from fall until 
May or June when it migrates to grain and spends the summer months 
there. Another species, living on the elm during the fall, winter and 
spring, passes to the apple for its summer residence, and a long list of 
aphids having alternating food plants is now known. 

Plant lice suck the sap from plants and often produce curling or mal- 
formation and even wilting of the leaves, frequently accompanied by 
discoloration. Root-attacking forms produce knots and deformities 
affecting the health of the plant, and young fruit becomes hard at the 
attacked spots and remains small. The punctures aphids make often 
enable the spores of fungi and bacteria causing plant diseases to enter the 
plants, and they may even transfer these from one plant to another. 
Among the diseases transferred thus are an oat blight, fire blight of the 
pear and cucurbit wilt. Indirectly by the honey dew in which spores can 
live for several days, it is probable that the diseases can also be widely 
distributed through the agency of other insects which visit and feed on 
honey-dew. In general a year when plant lice are abundant over a 
large part of the country is certain to result in great injury to plants of all 
kinds affected by these insects. 

Ants not only gather the honey dew the Aphids produce, but in some 
cases the relation is closer, particularly with root feeding species. The 
eggs of the corn-root louse for example, are gathered by ants in the fall 
and kept in their underground chambers during the winter. In the spring 
the ants place the insects on the roots of certain weeds but after the corn 
has begun to grow well, they transfer them to the corn roots where they 
visit them during the summer to collect honey dew. (See page 203.) 

Plant lice have many enemies which destroy great numbers of them. 
They are also affected by the weather, cloudy, wet periods being favor- 
able, though driving rains destroy many. 

In general the best control of plant lice is obtained by the use of 
nicotine sulfate 40 per cent used at a dilution of from 1 to 800 to 1 to 
1,000 parts of water. Where this cannot be obtained, kerosene emulsion 
or fish-oil soap solutions rank next as control. 



198 



APPLIED ENTOMOLOGY 



The Apple Aphids. — There are three species of plant lice which attack 
the apple more or less generally throughout the United States, and a 
fourth is injurious in some parts of the country. In addition, a woolly 
species feeding both on the twigs and roots is of importance and will be 
treated later. 

The three species referred to are the Green Apple Aphis (Aphis pomi 
DeG.), the Rosy Apple Aphis (Anuraphis roseus Bak. and Turn.) and 
the Apple Grain Aphis (Rhopalosiphum prunifolice Fitch), the latter until 
recently believed to be the same as a European species and generally 
known therefore, as the European Grain Aphis. All three lay their eggs 
in the fall on the twigs of the apple. In the spring the eggs of the Apple 
Grain Aphis hatch a week or 10 days before those of the other two. The 
young of all three kinds feed on the buds and become stem mothers which 
when full-grown, differ in appearance. 





t 


i 


- 


J 


I:- 


4 


1 


1^ 


1 


% 


f\ 




Fig. 1S8. Fig. 189. 

Fig. 188.^Green Apple Aphis (Ai)his pomi De G.), stem mother, about eight times 
natural size. {Modified from Cornell Agr. Exp. Sta. Mem. 24.) 

Fig. 189. — Rosy Apple Aphis {Anuraphis roseus Bak. and Turn.), stem mother, greatly 
enlarged. {Modified from Cornell Agr. Exp. Sta. Mem. 24.) 

The Green Apple Aphis stem mother (Fig. 188) has a uniformly green 
body, brown head and long, dark cornicles : the Rosy Apple Aphis stem 
mother (Fig. 189) is greenish but blended with purplish brown, and the 
cornicles are long, slender and dark; the body in this case is so dark as 
to be often described as blue: the Apple Grain Aphis stem mothers 
(Fig. 190) are yellowish-green, with a broad darker green stripe along the 
middle above, from which several side branches pass off, and with rather 
short, stout, yellowish cornicles. 

As the leaves develop the lice feed on them and in the case of the 
Rosy Apple Aphis produce much curling. This is usually less pronounced 
with the Green Apple Aphis and does not occur with the Apple Grain 
Aphis. 

After a generation or two on the apple, winged forms (Fig. 191) begin 
to appear and these migrate to summer food plants, except with the Green 
Apple Aphis which remains an apple feeder throughout the year. The 



THE HOMOPTERA 



199 



Rosy Apple Aphis migrates to species of plantain, particularly the nar- 
row-leaved plantain and it is noticeable that the spread of this plant 
louse over the country has closely followed that of this introduced weed. 
The Apple Grain Aphis migrates to small grains such as wheat and oats. 
On these summer food plants generation after generation is produced 
but in the fall a migration back to the apple occurs and here a sexual 
generation appears and eggs are laid which hatch the following spring. 
In some cases the Apple Grain Aphis may winter over close to the ground 
on the grain, not returning to the apple. The winged form of the Rosy 
Apple Aphis during the summer months has a pinkish or reddish body 
which has led to its being given its common name. 

In the middle West the Clover Aphis {Ayhis hakeri Cowan) has a 
similar life history to those just outlined, but during the summer lives on 
clovers. 





Fig. 190. Fig. I'Jl. 

Fig. 190. — Apple Grain Aphis (Rhoj)aloiiiphum prunifolice Fitrh), stem mother, greatly 
enlarged. {Modified from Cornell Agr. Exp. Sla. Mem. 24.) 

Fig. 191. — Winged Migrant of Green Apple Aphis, greatly enlarged. {Modified from 
Cornell Agr. Exp. Sta. Mem. 24.) 



The chief injury to the apple caused by these insects is that their 
feeding on the buds checks their growth. The leaves are also curled and 
growth is reduced. 

Control of Apple Plant Lice. — Destruction of the winter eggs l)y 
sprays has not thus far been very successful. The best control known 
at present is to very thoroughly spray the trees just as the buds are 
beginning to open and the eggs hatch, with the standard formula of 
nicotine sulfate 40 per cent. If an application of lime-sulfur is desired 
the nicotine sulfate can be added to that, provided the soap be left out. 
A second application about 2 weeks later, is sometimes desirable. In case 
nicotine sulfate cannot be obtained, kerosene emulsion, 1 part to 9 
of water, or fish-oil soap, 1 lb. in 5 to 7 gal. of water may be used instead. 

The Woolly Apple Aphis {Eriosoma lanigera Hausm.). — This European 
pest has been in the United States for many years and is widely dis- 



200 



APPLIED ENTOMOLOGY 



tributed. The adult is a small insect more or less completely covered by 
white, cottony or woolly threads of wax which practically conceal the 
louse beneath. Recent studies have shown that in most cases at least, 
the winter is spent in the egg stage in crevices in the bark of the elm. 
The eggs hatch in spring and the young lice pass to the buds and attack 
the leaves when these develop, causing them to become deformed, curled 
and clustered together forming "rosettes." Several generations partici- 
pate in this work. 

During the later spring months winged migrants are produced and 
these pass to the apple, hawthorn and a few other related trees where 

they locate on the under side of the leaves 
and produce young which crawl to thin 
places, wounds or water shoots and there 
locate and reproduce during the summer and 
fall (Fig. 192) until cold weather comes on, 
when migrating forms are produced which 
return to the elm where the eggs are laid. 

This life history is complicated by the 
fact that during the summer some of the 
plant lice migrate from the branches of the 
apple tree to its roots and feed there, pro- 
ducing knots and swellings which interfere 
with the nutrition of the plant, and if suffi- 
ciently abundant may cause its death. These 
lice are believed to remain on the roots the 
year around, generation after generation, but 
with their ranks recruited from time to time 
by migrants from the aerial members. Some 
of the latter also, are believed to remain on 
the apple all winter as hibernating nymphs. 

The amount of injury to the apple caused 
by this insect above ground is not very great 
except perhaps on nursery trees. Woolly spots 
at scars and wounds on the branches, notice- 
able chiefly in the fall, are not abundant enough to affect the trees 
much, usually. The root form, however, is sometimes quite injurious, 
particularly south of the latitude of Washington, and young orchards 
may suffer severely. 

Control. — The waxy "woolly" threads covering the bodies of these 
insects make control more difficult by spraying than would otherwise 
be the case, as the threads repel the spray. Nicotine sulfate 40 per cent, 
standard formula, or kerosene emulsion 1 part to 9 of water, driven with 
much force are about the only treatments for the aerial forms which have 
given much success. It is evident that elms growing near apple trees 




Fig. 192. — Apple twig show- 
ing Woolly Apple Aphis 
{Eriosoma lanigera Hausm.) 
and swellings of the twig pro- 
duced by their attacks. About 
twice natural size. (Orioinal.) 



THE HOMOPTERA 



201 



directly favor the successful migration of this pest, and as far as possible 
therefore, no elms should be allowed to grow near apple orchards. 

For the root torm, when sufficiently injurious to make it pay, removing 
the earth to a depth of six or eight inches over the root area and pouring 
kerosene emulsion or nicotine sulfate diluted as above, over this exposed 
surface, using enough to thoroughly wet the ground, has given good 
results. 

Nursery stock affected can be dipped in the lime-sulfur wash or 
in these materials, when dug either for transplanting or sale, and as 
the Northern Spy seems to be rather free from this pest, using trees 
grown on stocks of that variety is desirable. 

The Grape Phylloxera {Phylloxera vitifolice Fitch). — This aphid is a native 
of America and attacks the grape. Native American vines, however, are resis- 
tant to its work to a considerable degree, so that injury to them is not serious. 




Fig. 193. — Under surface of Grape leaf showing galls produced by the Grape Phylloxera 
(Phylloxera vitif olios Fitch). Somewhat reduced from natural size. (From Riley, U. S. 
D. A.) 

The European grape (Vitis vinifera) on the other hand, is very susceptible to 
its attacks and when the Phylloxera reached Europe about 1860, it became very 
destructive, causing the loss of over two million acres of vineyards before any 
successful checks to the insect were discovered. In this country it reached 
California where the European grape is also grown, about 1874 and has been the 
cause of great injury there also. 

The insect lays its eggs, one per female, on old wood of the grape in the fall, 
and these eggs hatch the following spring into tinj' hce which locate on the upper 
surface of the young leaves and begin to suck the sap. This causes the leaf to 
become depressed at each place where a louse is at work, so that galls (Fig. 193) 
projecting from the under surface are soon produced, in which the insects live. 
Upon becoming full-grown these lice lay eggs in the galls and the young which 
hatch from them pass to other parts of the leaves and produce galls of their 



202 



APPLIED ENTOMOLOGY 



own. This process continues through the summei but in the fall the young 
desert the leaves (Fig. 194) and work down to the roots and rest until the foUow- 




FiG. 19'4. — Grape Phylloxera: a, galls on grape roots; h, galls enlarged, showing the 
insects; c, Phylloxera from a root gall: b and c enlarged. (From Sanderson, Insects Injuri- 
ous to Farm, Garden and Orchard; after Marlatt, U. S. D. A.) 




Fig. 195. — Grape root showing galls caused by Phylloxera. (From Berlese.) 



ing spring. Then they attack the roots, forming swellings (Fig. 195) which on 
young rootlets stop their growth, and on the larger ones cause decay which spreads 
around the root and kills it beyond that point. 



THE HOMOPTERA 203 

During the latter part of this second season some winged forms (Fig. 194) 
are produced and these make their way up to the surface of the ground and 
migrate to other vines where they lay eggs. These produce both male and 
female plant lice and each female lays a single fertilized egg which winters over. 

This 2 year life and the production of leaf galls is not always necessary to 
the continued existence of the insect however. The root form generally goes on, 
brood after brood, particularly on the European grape, without the formation 
of leaf galls, and while young from the leaves may probably pass to the roots 
at any time during the summer, the migration of root forms to the leaves is 
unknown. Apparently then, the life history just outlined applies to American 
varieties of the vine, but in the case of the European species, while the lice may 
pass to the roots they do not usually, at least, seem to migrate in the reverse 
direction, the insects coming from fertilized eggs passing directly to the roots. 
Root forms may spread to other plants through the soil. 

Control. — Four methods of control have been made use of for this pest, viz., 
the injection of Carbon disulfid into the soil close to the roots; flooding the vine- 
yard with water; planting in very sandy soils; and the selection of resistant 
varieties. The first of these has given fair results where the soil is loose, deep and 
rich, but is most successful in cooler locations, and here the insect is least abun- 
dant. It is also rather expensive and has therefore largely been replaced by other 
treatments. 

Submersion of the ground under water is a better method, but obviously 
cannot be made use of in most cases. The vineyard must be kept covered with 
at least six inches of water in order to drown the lice and unfortunately the best 
time to do this is during the summer when the vines are most liable to be injured 
by this treatment. The time chosen therefore, is after the vines have stopped 
active growth but before the lice have become dormant. In California this is 
generally some time in October. Flooding then should last from a week to 
10 days: later in the season it must be extended and in the winter months 35 
to 40 days of treatment is necessary. 

Planting in sandy soil is, for some reason not understood, a protection of the 
vines against Phylloxera, particularly where it contains a high percentage of 
siliceous sand. It is not always possible to locate vineyards on such soil however. 

The selection of resistant varieties of the grape is now the favored method of 
control. With such varieties the insects when present on the roots do not in- 
crease rapidly and the diseased tissue of the swellings on the roots does not go 
deeper than the bark, leaving the roots proper quite healthy. At the present 
time the grafting of vinifera varieties on resistant stalks which preserves the 
resistant properties of the roots while producing the vinifera quality of grapes 
so much desired, seems to give the best results in vineyards, though the proper 
combination of different varieties of the two calls for a detailed knowledge of 
the subject in actual practice. 

The Corn Root Aphis {Aphis maidi-radicis For.bes). — This insect, though it* 
can hardly be regarded as universaUy distributed through the United States, 
is both a serious pest of corn over a large area and because of its interesting rela- 
tion with ants, an interesting species. It appears to occur throughout the 
eastern United States as far west as South Dakota and Colorado and south to 
South Carolina, Louisiana and Texas, but its destructive work mainly covers the 
territory from New Jersey to South Carohna and west to the Mississippi River, 



204 



APPLIED ENTOMOLOGY 



The eggs of this aphid hatch eai'ly in spring and from 10 to 22 generations 
(Figs. 196 and 197) are produced during the season. As cool fall weather 
appears, a generation of sexual individuals (Fig. 198) appears and these lay- 
eggs which pass the winter. During this season they may be found in the 
ground in nests of several kinds of ants but most 
frequently in those of the little brown ant, Lasius niger 
americanus. They are oval, black and glistening and 
are sometimes found in small piles in the nests of the 
ants. In cold weather the ants carry the eggs down 
below the frost and on warm days bring them up to 
warmer levels. In spring, when various weeds such as 
smartweed, begin to grow, the ants tunnel along the 
roots of these weeds and place the young lice as they 
hatch, on them to feed. Later, when corn roots 
become available the ants transfer the lice to them, 
where they and their descendants feed during the rest 
of the season. Winged migrants are produced after a 
generation or two and these individuals spreading, are 
taken to corn roots by ants which may find them. All 
summer and fall the ants care for the lice, taking them 
from one plant to another and collecting from them the 
honey-dew upon which the ants feed. In the fall when 
the eggs are laid these are gathered by the ants and 
stored in their nests over winter. 
Where the Corn Root Aphid is abundant it becomes a serious corn pest, 
dwarfing the corn and turning the leaves yellow or reddish and sometimes destroy- 
ing the plants, particularly when weather conditions are also unfavorable. 




Fig. 196.— Corn Root 
Aphis ( Aphiti maidi- 
radicis Forbes) ; wingless, 
viviparous female. 
Greatly enlarged. {From 
U. S. D. A. Bur. Ent. 
Bull. 85, Part VL) 




Fig. 197. — Winged, viviparous female of the Corn Root Aphis, greatly enlarged. 
U. S. D. A. Bur. Ent. Bull. 85, Part VI.) 



{From 



Control. — Rotation of crops is of much value as a control, for as the lice 
cannot migrate until their second generation, corn planted on land where they 
are not already present will get well started. Fertilization and frequent cultiva- 



THE HOMOPTERA 



205 




tion to produce vigorous growth will aid in this. The worst injuries are usually 
where corn is planted to follow corn and therefore where this pest is already 
present in the field from the preceding- year. Any method which will destroy 
the nests of the ants which care for the lice will also be helpful, and deep plowing 
and harrowing both in late fall and early spring has 
proved of value for this purpose. 

Some plant lice attack evergreens and pro- 
duce rather soft, fleshy galls, generally at the 
bases of the outer shoots. These appear during 
the spring months and are of full size by mid- 
summer. They then dry and crack open, showing 
little cavities occupied by the plant lice which now 
leave the galls for other parts, either of the same or 
some other kind of tree, according to the species 
concerned. The gall formation interferes with the 
growth of the tree by preventing wholly or in 
part, the circulation of the sap in the shoot at the 
base of which the gall is located, and this results, 

by the death or checking of the growth, in trees which look thin rather 
than dense, and in some cases they may become worthless as lawn 
ornaments. In the East the spruce is often seriously injured in this way. 

Many kinds of plant lice often become seriously abundant for periods 
of 2 or 3 years, then disappear for a time. The Potato Plant louse, the 
Pea louse, the Beet-root louse. Cherry plant lice and others have all been 
destructive for a year or two at a time within the last decade, and similar 
outbreaks of these or others may be expected any year. Wherever it is 
possible, spraying thoroughly upon the first appearance of the lice, with 



Fig. 198. — Oviparous 
female of the Corn Root 
Aphis, greatly enlarged. 
{Frum U. ,S'. D. A. Bur. 
Ent. Bull. 8.5, Part VI.) 




Fig. 199. — Aphid parasite (Lysiphlebus testaceipes Cress.) ovipositing in the body of a 
Spring Grain Aphis. Greatly enlarged. (From U. S. D. A. Bur. Ent. Bull. 110.) 

nicotine sulfate, kerosene emulsion or fish-oil soap should be resorted to 
as measures of relief. If for any reason this cannot be done and no special 
method of control seems available, dependence must be placed upon 
climatic influences and insect enemies to check these pests, and this will 
occur within 2 or 3 years in nearly everj^ case. 

Among their many enemies is one group of tiny insects which makes a 
specialty of attacking plant lice. An insect of this group will select a 



206 



APPLIED ENTOMOLOGY 



louse (Fig. 199) and, facing it, will thrust its abdomen forward beneath 
its body and drive its ovipositor into the louse. The young parasite 
hatching from an egg thus deposited, will feed upon 
the aphid whose body becomes distended and 
generally changes color after a time and finally 
dies adhering to the plant on which it was. When 
the parasite has completed its development within 
the body of the louse it escapes by cutting a 
circular, lid-like opening through the skin (Fig. 200), 
and lice attacked and killed in this way are often 
very plentiful during and particularly toward the 
end of a period of destructive abundance of these 
insects (see page 344), 

Family Ale3rrodidaB. — The adults of the insects 
belonging in this family (Fig. 201) are very small 
and have four wings which are broadly rounded 
and have a white dust covering them, which has 
led to calling the group the White Flies. Occa- 
sionally the wings have dark spots or streaks. The 
eyes are often constricted in the middle or even 
divided into two parts. The body is generally 
yellowish, though in some species it may be of 
other colors. 

The nymph on hatching, crawls around for a 
short time before settling down on a leaf, then in- 
serts its rostrum in the tissues and begins to feed. 
After molting the insect becomes quiet, with its legs and antennae much 
reduced, and thereafter does not move from its location until it becomes 




Via. 200.--Plant Lice 
killed by parasites. Up- 
per figure shows the 
circular piece of chitin 
cut by the parasite in 
escaping, but still at- 
tached. Lower figure 
shows the parasite just 
escaping. Much en- 
larged. (From U. S. D. 
A. Bur. Ent. Bull. 110.) 




Fig. 201. — Adult White Flies twice natural size. {From Britton, Second Report Ent. Conn. 

Agr. Exp. Sta. 1902.) 

adult, and wax which may have been produced before the first molt, 
now becomes more noticeable. This wax may take the form of a fringe 



THE ROM OPT ERA 



207 



around the sides and may more or less cover the body. The animal after 
its third molt differs so from its former appearance that this stage is 
often called a pupa, and as the following molt produces the adult there 
is evidently quite a metamorphosis to justify the use of this term in the 
group. Honey-dew is produced by these insects. 

White Flies are essentially tropical though a few species live in the 
northern United States. In greenhouses everywhere the Greenhouse 
White Fly {Aleyrodes vaporariorum Westw.) is too often a serious pest, 
for it multiplies rapidly and the tiny nymphs (Fig. 202) are not generally 
noticed in time to check their increase before the plants have suffered 




Fig. 202. — Nymphs of the White Fly on underside of a leaf, enlarged twice. 
Britton, Second Rept. Ent. Conn. Agr. Exp. Sta. 1902.) 



(From 



greatly. When they are abundant, fumigation for 3 hr. at night, using 
between j^s and }-q oz. of sodium cyanid to each 1,000 cu. ft. of space in 
the greenhouse should kill all but the eggs and some of the pupae, and 
repeating this treatment twice afterwards at intervals of 2 weeks should 
destroy the others in the stages to which they will have then progressed. 
If for any reason this treatment is not desirable, syringing the plants 
with fish-oil soap using from 1 to 13^2 oz. per gallon of water, giving 
particular attention to the under surface of the leaves will give some relief. 

In the Southern States and in California, white flies attack citrus fruits and 
cause much injury. Several species are more or less concerned, the most impor- 
tant one being the Citrus White Fly (Dialeurodes citri Ashm.). These insects 
usually check the growth of the tree and fruit, reducing the yield and its size, 
and also by the production of honey-dew, induce the growth in this of a fungus 
called "sooty mould" which interferes with the ripening of the fruit and is also 
believed to affect its flavor, besides making it look objectionable, so that fruit 
partly covered with the mould must be cleaned before shipping. The reduction 
of the vitality of the tree by these insects also favors the more active development 
of other citrus insects and of diseases. 



208 APPLIED ENTOMOLOGY 

Certain fungi live on the white flies, however, and are of assistance in their 
control, but as they need certain weather conditions for their best growth during 
about 3 months, they can rarely accomplish more than a third of the amount 
of control necessary. 

Spraying with paraffin-oil emulsion prepared according to special directions 
has proved to be a successful method of control for citrus white flies, and miscible 
oil has also given good results. In either case the material as applied should 
contain about 1 per cent of oil. 

Family Coccidse (Scale Insects). — These are remarkable insects 
having been much modified and changed in appearance from the more 
ordinary forms. Without attempting an accurate classification, they 
may be grouped under three heads: the armored scales, the soft scales, 
and the mealy bugs. 

The mealy bugs are the least degenerate of the three groups. In 
them the females preserve their body segments, eyes, antennai and legs, 
and can move about. They secrete a waxy material, usually as long 
cottony threads or plates, more or less covering their bodies and some- 
times forming a large egg sac at the hinder end. In the female soft 
scales the antennae and legs are not lost but they become reduced to 
such an extent that though the adult can move about somewhat, it 
seldom does so. Wax when secreted, is usually to form a sac at the hinder 
end of the body enclosing the eggs, and the skeleton on the back of the 
insect becomes very much thickened, forming a scale, often very convex, 
strong and protective, though seemingly softer than in the armored 
scales. In this last-named group the female loses antennae, eyes, and 
legs, and secretes a waxy scale, with which the molted skins from the 
body are felted together, forming generally a rather flat and very tough 
scale. The metamorphosis in the females of all three groups is incom- 
plete. In some cases the females are fertilized before they have attained 
full size and grow considerably afterwards. 

The males develop much as do the females, at first, though not losing 
any of their parts by degeneration. After reaching full size, however, 
they pupate and emerge from the pupa as very tiny insects with only one 
pair of wings and no mouth parts. Thus in the scale insects we have the 
remarkable fact that while in the males there is a complete metamorpho- 
sis, in the females it is incomplete. Whether the former was the original 
condition in the group, and the females through the degeneration con- 
nected with their mode of life have changed to an incomplete meta- 
morphosis, or whether this was the primitive condition and complete 
metamorphosis has been developed in the males, is unknown, though the 
other Homoptera all have an incomplete metamorphosis. 

About 2,000 species of scale insects are known, attacking nearly all 
kinds of trees and shrubs, and sometimes other plants as well. Many 
have an almost incredible rapidity of increase, and when under favorable 



THE HOMOPTERA 



209 



conditions, this results in the death of the plant they are on. A few are 
beneficial to man. Thus the bodies of a scale feeding upon cactus, when 
dried and prepared, furnish the dye known as Cochineal. Shellac is 
obtained from the excretions produced by another scale, and China wax, 
used as furniture polish, comes from a third species. Most scale insects, 
however, are injurious and fail to compensate for the injury they cause by 
producing anything of value. 

Among so many serious pests, only a few can be considered in detail 
here. Taking the armored scales first, these are the Oyster shell, the 
Scurfy and the San Jose Scales, with brief reference to a few others. 

Armored Scales 

The Oyster-shell Scale {Lepidosaphes ulmi L.). — This insect, native 
to Europe, has been so long in this country that it is now very generally 
distributed. It is chiefly an enemy of the apple, pear, poplar, willow, 
ash and lilac, but is often found on other plants. It feeds on all parts 
covered by bark, and the male scales are also often found on the leaves. 




Fig. 203. — Female scales of the Oyster-shell Scale (Lepidosaphes ulmi L.) on a twig, about 
twice natural size. {Original.) 



The full-grown female scale (Fig. 203) is about one-eighth of an inch 
long and has much the form of an oyster shell, one end narrowly rounded, 
the other rather more broadly so, and the shell as a whole usually bent 
somewhat to one side. It is brown to gray in color, varying with age, 
and to some extent, the plant it is on. During the winter examination 
of the scale will show beneath it at the narrower end, the dead body of the 
insect, and behind it from 15 to 100 tiny whitish eggs. These hatch the 
following May or June, according to the advancement of the season, into 
very small whitish nymphs or "crawling young," which are extremely 
delicate and with no scale. These young crawl out from beneath the 
parent scale and wander about for a few hours or even a day or so, seeking 
for places where they may settle: then each thrusts its beak through 
the bark and begins feeding, and degeneration of eyes, antennse and 
limbs, and the secretion of wax over the body begins. To this secretion 
the molted skin is added at each molt, making a very tough, hard, cover- 

14 



210 APPLIED ENTOMOLOGY 

ing scale. The Insect beneath this becomes adult after a time and 
following the laying of its eggs, dies. In the northern states the eggs are 
laid in August or September, but in the middle states and farther south, 
the earlier seasons permit hatching enough earlier in the season for the 
adult condition to be reached and the eggs laid by midsummer, and these 
eggs soon hatch and produce egg-laying adults before the following 
winter. Thus, this insect though having but one generation each year 
in the more northern states, has two from about the latitude of New 
Jersey southward, except at such altitudes as to produce northern 
conditions. 

Many of the male crawling young go to the leaves to settle and the 
scales they form are smaller and somewhat different in shape from those 
of the females. Beneath them they attain their growth, then pupate, 
still under their scales, and at the end of this process emerge as very 
small two-winged adults without any mouths or mouth parts, having un- 
dergone a complete metamorphosis. 

Control. — These insects are least protected while crawling young, and 
as they are sucking forms, a contact insecticide should be applied 
while they are moving about or at least before they have had time to 
produce scales covering themselves. The usual treatment therefore is 
to spray with 1 part of kerosene emulsion to 9 of water, or with Nicotine 
sulfate 40 per cent, 1 part, water 800 to 1,000 parts, as soon as the young 
appear. They are so small, however, that it is very difficult to reach 
them all with the spray, and as all do not hatch at the same time, a 
second application about 10 days after the first, is desirable. Winter 
spraying with lime-sulfur wash is also a fairly good treatment. Where 
neither of these methods proves effective (as is sometimes the case), 
spraying in spring, shortly before the eggs hatch, with linseed oil emulsion, 
has worked well. This is prepared as follows: 

Raw linseed oil 1 gal. 

Hard soap I2 lb. 

Water, to make 10 gal. 

Dissolve the soap in the water; add the oil and churn through a 
pump as for kerosene emulsion until thoroughly mixed (it does not 
thicken up like the latter) and spray. 

The Scurfy Scale {Chionaspis furfura Fitch). — This insect is a native 
of America and is usually less abundant in the more northern states than 
elsewhere, attacking the apple, pear, mountain asn, currant, gooseberry, 
hawthorn, Japanese quince and other plants. The full-grown female 
scale (Fig. 204) is shorter and broader than the Oyster-shell scale, 
and when perfect in outline, rather pear-shaped, and dirty white in color. 
Its life and habits are much the same as those of the Oyster-shell scale. 



THE HOMOPTERA 



211 



but the eggs are fewer in number and dark purple in color, as are also the 
crawling young which usually hatch a few days later in the season than 
the other species. Control methods are the same as for the Oyster-shell 
scale. 




Fi(i. 204. — Scurfy Scales (Chionaspis furfura Fitch). Male scales at right, female 
scales at left. Left hand figure greatly enlarged ; the other two somewhat enlarged. {From 
U. S. D. A. Farm. Bull. 723.) 



The San Jose Scale (Aspidiotus perniciosus Comst.). — This is one of 
the most serious pests among the scale insects. Its original home was 
probably China, but H appears to have reached California about 1870 
and since then has spread practically all over this country. It has a 
wide range of food plants, on many of which it thrives sufficiently to 
quickly kill them. The plants which suffer most from its attacks are 
the fruit trees and currants, the dog-woods, thorns, poplars, ornamental 
cherries and plums, hardy roses, willows, lilacs and lindens; and even 
maples and elms are sometimes attacked, the total list of plants upon 
which it has been found numbering over a hundred. It feeds on all 
parts of the plant above ground, even including the fruit. 

The full-grown female scale (Fig. 205) is about the size of a pin head, 
nearly circular in outline and rather flat, sloping gradually upward from 



212 



APPLIED ENTOMOLOGY 



its edge to near the center where a shght circular depression surrounds 
the raised center or "nipple" itself. It is brownish-gray in color when 
adult, but in earlier stages may vary from this. The adult male scale 
is somewhat smaller, more oval in outline, and with the nipple not cen- 
trally placed but nearer one end. 

At the beginning of the winter season specimens of this scale of 
practically all ages occur, but probably only those from about one-third 
to one-half or two-thirds grown survive the winter. In the spring these 

individuals resume their feeding on 
the sap and after a time the males 
appear. In the northern states 
this condition is hardly reached 
before the middle of May, but at 
Washington, D. C. it comes early 
in April, and farther south still 
earlier. After mating, the females 
continue to grow and about a 
month later the first young appear. 
These do not, in the San Jose 
Scale, hatch from eggs laid by the 
parent but the young are born 
alive; i.e., this insect is viviparous. 
These young are produced, a few 
every day or two, and the parent 
lives for a month or more, pro- 
ducing an average total of about 
400 young. These resemble the 
crawling young of the scales already 
considered, except that they are 
lemon yellow in color, and they 
crawl about and settle down to feed in the same way. The scale 
now begins to appear, at first as white waxy threads over the back, 
which soon mat together to form a pure white covering. As the 
nymph beneath molts, the molted skins are added to this and variations 
in color of the scale appear. Sometimes the scale of the partly grown 
insect may show white, black and gray, varying in arrangement according 
to the completeness with which the different parts have combined, but 
before maturity it becomes a quite uniform grayish-brown. The young 
become adult in a little over a month and then themselves begin to 
produce young, and in the northern states there are usually at least 
three generations in a season, while in the south there are four or even 
more. The generations overlap, the earliest young produced by the 
second generation for example, sometimes appearing before the last born 
of the preceding one, which results in the almost constant presence of 




Fig. 205. — San Jose Scale (Aspidiotus 
pcrniciosus Comst.) : adult female scales 
enlarged about five times. {From Houser, 
Ohio Agr. Exp. Sta. Bull. 332.) 




THE HOMOPTERA 213 

crawling young on an infested tree, from the time the first one appears 
until reproduction is stopped by cold weather. Assuming the production 
of four full generations in a season, equally divided between the sexes, 
and with no loss in number from death by accident or other causes to 
reduce the number produced, we have a total of 3,216,080,400 in individ- 
uals as the descendants during one season from a single pair. Fortu- 
nately, many never reach maturity, or an infested tree would often 
be sucked dry before winter. 

The San Jos^ Scale has a number of parasites which are sometimes 
quite effective, destroying a large per cent of the scales in some localities, 
but with such an enormous power of increase of the pest, even a high 
degree of parasitism fails to give the relief needed. A few predaceous 
insects are also known, which feed upon the 
scale. Most noticeable among these is the 
Twice-stabbed Lady Beetle {Chilocorus hivulnerus 
Muls.), a small black beetle (Fig. 206) with two 
red spots. It is nearly circular in outline, very 
convex and is about one-eighth of an inch long. 
A fungous disease also attacks the scale, par- 
ticularly in the South, but parasites, predaceous ^ „„^ ^ . , , , , 

•^ ' ^ 11111 ^^^- 200. — Twice-stabbed 

foes and diseases together, generally fail to hold Lady Beetle (Chilocorus bi- 

it entirely in check. vulnerus Muls ): a, adult; b 

. larva enlarged: real length 

A lady beetle closely resembling the Twice- shown by the hair lines, 
stabbed Lady Beetle is an enemy of the scale in (f'"°"* Sanderson and 

. II- Jackson, Elementary Ento- 

China, the native home of the pest, and this moiogy. after Riley.) 
insect has been brought to the United States 

with the hope that it might do effective work here, but thus far, for 
various reasons, it has failed to accomplish much. 

Control. — Spraying as for the Oyster-shell Scale is useless, for that 
treatment is based upon the destruction of the delicate, crawling young, 
by one or at most two applications. With the San Jose Scale, however, 
the young do not all appear at about the same time, but are present 
practically from May or June according to the latitude of the locality, 
until winter. To use this method successfully therefore would require 
spraying about every 2 weeks or so for a period of at least 5 months — 
a treatment manifestly impracticable. 

Stronger materials are therefore used, during the dormant season, 
when the tree is least liable to injury by the spray, and when a more 
thorough application can be made, the leaves having fallen. For this 
purpose the lime-sulfur wash and miscible oils are generally used (see 
Chapter VIII). At times injury to the trees has been observed following 
the use of miscible oils, but on the other hand these materials spread 
better over the tree than the lime-sulfur. Many persons now make a 
practice of spraying every third winter with miscible oil, but using the 
lime-sulfur at other times. 



214 



APPLIED ENTOMOLOGY 



In some cases summer treatment may be desirable where the scale 
is increasing rapidly, to preserve the tree until winter gives an oppor- 
tunity for the regular application. In such cases a greater dilution of the 
lime-sulfur becomes necessary, and with stone-fruit trees the self-boiled 
material should be used. 

Fumigation with Hydrocyanic acid gas is the most effective treatment 
for the San Jose Scale, but the cost of the tents large enough to cover all 
but the smallest trees is so great that this method is made use of only for 
fumigating nursery stock after it has been dug, in houses built for that 
purpose. 




a b 

Fig. 207.— Rose Scales (Aulacaspis rosce Bouche): a, female scales; h, male scales. 

Considerably enlarged. {From Houser, Ohio Agr. Exp. Sta. Bull. 332.) 

The Rose Scale {Aulacaspis rosce Bouche). — Generally distributed in the 
United States on raspberry, blackberry, dewberry, rose, pear and some other 
plants. Female scales (Fig. 207) white with more or less yellow at margin; 
nearly circular, about one-tenth of an inch in diameter. Male scales white, nar- 
row, very small. Plants thickly infested appear as though sprayed with white- 



THE HOMOPTERA 



215 



wash. Winters in various stages, so all may be present at almost any time. 
Two or three generations per year. Control by cutting out the worst infested 
stems during the winter, and spraying with lime-sulfur as for San Jose Scale in 
early spring. Whale-oil soap (1 lb. in 1 gal. water) may also be used. . 

The Pine-leaf Scale {Clnonaspis pinifolioe Fitch). — Occurs generally in the 
United States on leaves of pine, and sometimes other evergreens. Female scale 
(Fig. 208) white, narrower than Scurfy Scale but varying to fit the width of the 
leaf: male scale much smaller. When abundant, whole branches may appear 




Fig. 208.- 



-Pine-leaf Scale (Chionaspis pinlfolice Fitch). Female scales on pine leaf, about 
twice natural size. {Original.) 



as though their leaves had been sprayed with whitewash. Two generations a 
year, purplish crawling young appearing in the northern states about the middle 
of May and the first of September, at which times spray with either kerosene 
emulsion or the linseed oil emulsion as advised for the Oyster-shell Scale. 

The Purple Scale (Lepidosaphes beckii Newm.). — -In the South and on the 
Pacific Coast this insect is very injurious to citrus plants, even on the fruit of 
which it is often seen. It greatly 
resembles the Oyster-shell Scale in 
appearance (Fig. 209) and size There 
are three or four generations each 
year. Control is usually by fumiga- 
tion with Hydrocyanic acid gas during 
the colder months. 





Fig. 210. 
about natural size. 



(Modified 



Fig. 209. 

Fig. 209. — Purple Scale (Lepidosaphes beckii Newm.), 
from Cal. Agr. Exp. Sta. Biill. 226.) 

Fig. 210. — Red Scale (Chrysomphalus aurantii Mask.) on a portion of a grape fruit. 
About natural size. (From, Cal. A(jr. E.Tp. Sta. Bull. 214.) 



The Red Scale {Chrysomphalus aurantii Mask.). — A serious pest of citrus 
trees in California. The female scale resembles the San Jose Scale in outline, 
but averages larger (Fig. 210) and the scale is transparent enough to allow the 
red body (yellow in a variety) of the insect to show through. The male scales 
are smaller and rather elongate. The life history is similar to that of the San 



216 



APPLIED ENTOMOLOGY 



Jose Scale, the young being born alive during the summer months. Control on 
citrus trees appears to be best obtained by fumigation with Hydrocyanic acid gas, 
but with deciduous fruit trees the lime-sulfur wash may be used. 

Occasionally the lenticels or breathing pores through the bark of 
plant twigs resemble armored scales, particularly the more circular 
ones. To determine in any case whether a debatable structure on bark 
is a scale or only a lenticel, it may be scraped with the finger nail. If it 
can be removed without breaking the bark (it may leave a whitish mark) 

the object is a scale, but if the bark is neces- 
sarily torn or broken to get it off, it may be 
assumed that it was a lenticel. 

Soft Scales 

As a group the soft scales are less injurious 
than the armored scales. Their rate of in- 
crease is less, their covering less protective, 
and their larger size renders them more cer- 





FiG. 211. Fig. 212. 

Fig. 211. — Tulip Tree Scale {Eulecanium tulipiferce) Cook), about natural size. 
{Original.) 

Fig. 212. — Black Scale {Saisettia oleoe Bern.), about natural .size. (From Col. Agr. 
Exp. Sta. Bull. 22.3.) 

tain to be reached by sprays. The largest one found in the United States 
is the Tulip Tree Scale, the adult female scale being about one-third of an 
inch in diameter (Fig. 211). An African soft scale is known which is 
about an inch long. 

The Black Scale (Saissetia oleoe Bern.). — This scale is found in nearly all 
parts of the world. It has a long Ust of food plants but is chiefly a pest on citrus 
trees and the olive, oleander, apricot and prune. In the United States it is 
therefore chiefly important in the South and West. The adult female scale is 



THE HOMOPTERA 



217 



from one-eighth to one-fourth of an inch in diameter and ahnost hemispherical in 
form, black in color and with ridges forming an "H" on the back (Fig. 212). 
The male scales are much smaller, long, narrow and flat. The eggs, from 50 to 
3,000, are for the most part, laid in May, June and early July, and the adult 
condition is reached early the next year, though variation from this is frequent. 
The young scales attack the leaves generally, but 
later pass to the twigs. The injury they cause by 
removing the sap from the tree is increased by 
the honey-dew they secrete, which falling in large 
amounts on fruit and leaves, forms an excellent 
material in. which a sooty fungus grows, and 
more or less cuts off light from the leaf surface, 
thus affecting the growth, and may also clog the 
stomata or breathing pores on the leaves, besides 
causing the fruit to look objectionable and need 
cleaning before its sale. Control of this pest is 
by Hydrocyanic acid fumigation between Septem- 
ber 1st and January 1st. Several parasites and 
enemies are known. One parasite, imported from 
South Africa, has at times done excellent control 
work, but has not been continuously effective. 

The Terrapin Scale {E ulecaivium nigrofasciatiuh 
Perg.). — This is a native insect attacking variou^ 
shade and fruit trees. The scale of the female is 
nearly hemispherical in form, about one-sixth of 
an inch in diameter, reddish, mottled and streaked 
with black (Fig. 213). This insect is viviparous, 
the young appearing in June and July and be- 
coming adult the following spring. The young 
spend a part of their life on the leaves before 
migrating to the stems. Control, when necessary, 
is by spraying just before the buds open in spring 
with miscible oil, using 5 parts of this and 3 parts 
of gasoline thoroughly emulsified, and 92 parts of 
water. 

The Cottony Maple Scale (Puluinaria vitish.). 
This insect attacks maple, linden, and other 
shade trees and plants. The scale of the adult 
female is rather flat, about one-fourth of an inch 
in diameter, and by midsummer generally lifted 
at one end from the twig it is on, by a projecting mass of cotton-like threads 
which surround 2,000 to 3,000 eggs (Fig. 214). These soon hatch and the young 
crawl to the leaves and cover themselves with a thin waxy coating. In fall they 
migrate to the twigs for the winter and become adult the following spring. When 
abundant the large, white, cotton-like masses make this a very noticeable insect. 
Contro is by spraying with a miscible oil, 1 part, water 15 parts, just before the 
buds open in the spring, or with kerosene emulsion, stock 1 part, water 3 parts. 




Fig. 213. — Terrapin Scale 
(Eulccanium nigrofasciatum 
Targ.), reduced somewhat 
(right hand figure), and some- 
what enlarged (left hand 
figure). {From Houser, Ohio 
Agr. Exp. Sta. Bull. 332.) 



218 



APPLIED ENTOMOLOGY 



The Hemispherical Scale {Saissctia heviis-phoerica Targ.)- — This scale is 
usually found in greenhouses and on house plants, such as ferns, palms, orna- 
mental asparagus, etc., and also out of doors in the South. It is very convex, but 
rather oval than hemispherical, about one -eighth of an inch long, brown in color. 
The partly grown young are very flat and with a notch at the hinder end. The 
eggs are laid during about a 3-month period in late spring, thus resulting in the ap- 
pearance of young during a long time. Fumigation 
as for the Black Scale, or dipping the plant in whale- 
oil soap 1 lb., water 2 gal., and after an hour rinsing 
the plant by dipping it in water, are fairly effective 
treatments. 

Mealy Bugs 

Mealy Bugs move about more or less freely 
during their life, as their limbs are not lost to 
any extent by degeneration. Nor is a scale 
present, the body being generally well covered 
by long, waxy threads, though in some cases 
waxy secretions forming plates connected with 
the body are produced. 

These insects are inhabitants of warm cli- 
mates and in the North are found only in green- 
houses and on house plants. 





Fig. 214. Fig. 215. 

Fig. 214. — Cottony Maple Scale (Pulvinaria vitis L.), about half natural size. 
(Modified from Felt, N. Y. State Miis. Mem. 8.) 

Fig. 215. — Citrus Mealy Bug {Pseudococcus citri Risso.), enlarged. 

The Citrus Mealy Bug (Pseudococcus citri Risso). — This insect attacks many 
plants and is a serious pest on citrus plants, feeding 'on the roots, stems, leaves 
and fruit, gathering in large clusters on the last. It produces a large amount of 
honey-dew, on which the sooty fungus already referred to grows. The adult 
females, pale yellow in color and well covered by a th ck waxy secretion (Fig. 215), 
are one-fourth of an inch long. The 300 to 500 eggs are laid in loose, white cotton- 
like masses, chiefly during fall and winter, and young and adults move about 
freely, the former becoming adult before the following summer. The cottony wax 
covering the insects renders them particularly difficult to reach with sprays. 
The best spray thus far found is a carbolic acid emulsion. To prepare this take 
8 gal. of water and boil, adding 8 lb. of soap. After this has dissolved, add 1 lb. 
crude carbolic acid and boil 15 to 20 min., which will give a thick, creamy emul- 
sion. To spray, dilute 1 gal. of this with 20 gal. of water. Spray between 



THE HOMOPTERA 



219 



October and March. Hydrocyanic acid fuinigatiou lias also given satisfactory 
results, especially with light doses frequently repeated. A number of natural 
enemies are of some value against this insect. 

The Long-tailed Mealy Bug {Pseudococcus longispinus Targ.).— This is 
often found in greenhouses attacking many kinds of plants. The bodies of adult 
females vary from yellow to gray, and the young are born alive, there being 
apparently several generations each year. Hydrocyanic acid fumigation seems 
to be the most successful treatment for these insects. Nicotine sulfate may 
also be used. 

The Cottony Cushion Scale or Fluted Scale {Icerya purchasi Mask.). — 
This serious pest of citrus and many other plants, apparently reached 
California from Australia about 1868 and by 1880 had spread all over 
the citrus-growing regions of the State and was threatening the destruc- 
tion of the entire citrus fruit industry. 




Fig. 216. — Cottony Cushion Seale {Icerya purchasi Mask.) and its lady beetle enemy, 
the Vedalia (Novius cardinalis Muls.): a, larvae of the Vedalia feeding on a Seale; h, pupa 
of the Vedalia; c, adult Vedalia; d, twig with the Scales and lady beetles, a, greatly 
enlarged; real length of h and c shown by hair lines; d about natural size. {From Sanderson 
and Jackson, Elementary Entmology: after Marlatt, U. S. D. A.) 

Investigation showed that in Australia it had an enemy known as 
the Vedaha {Novius cardinalis Muls.), a lady lieetle, and these were 
finally brought to California and colonized in the orange groves, where 
they attacked the scales so effectively that in the course of a few years 
these were brought under control, and now only an occasional local 
outbreak makes the scale of importance. When this happens, the in- 
troduction of the lady beetles to that region is soon sufficient to check 
all injury. In later years the scale has appeared in Portugal, South 
Africa and elsewhere, and when the introduction of the Vedalia into those 
regions has successfully followed, the scale has soon become relatively 
unimportant. 

The female scale has a red, yellow or brown body. It lays its 400 



220 APPLIED ENTOMOLOGY 

to 1,000 eggs in a large cottony mass formed at the hinder end of the 
body, the upper surface of the mass being grooved or fluted (Fig. 216). 
There are several generations in a season. 

Several of the scale insects treated in this chapter furnish good illustra- 
tions of the way in which nature works to preserve a balance in the 
insect world. In the first place it should be noticed that our native 
scales are often found with tiny circular holes in them showing where 
parasites after having fed on the insect beneath, have made their escape. 
Other scales, long in this country, such as the Oyster-shell Scale, now 
have numerous parasites, some of which are also enemies of other kinds 
of scales, and in fact may be considered as scale enemies in general, or at 
least of most scales of the same section. New parasites also appear 
from time to time as enemies of scales, such as a tiny insect, Prospaltella 
perniciosi Tower, first discovered about 1912, which at times has done 
remarkably good work against the San Jose Scale. But when a new 
scale or other insect native elsewhere, establishes itself in this country, 
one of the factors at least in its success here, must be that none of its 
parasites in the locality whence it came, accompanied it in its transfer. 
If under these circumstances, climatic and other conditions prove 
satisfactory, we have a case of an insect set free from all restraint, to 
work its destruction with no check, at least until some insect already 
present shall select it as a new and satisfactory food. This was evidently 
the case with Prospaltella and the San Jose Scale, already mentioned. 
In the meantime, however, years of destruction may elapse before any 
such check will appear, and the possibility of obtaining its special enemies 
from its native country appears to offer much in the way of quick relief. 
This "bug vs. bug" idea as it has been called, has a strong appeal to those 
suffering losses from the attacks of a newly introduced pest, and it has 
therefore been widely exploited. 

Probably the first attempt to carry out this idea was the introduction 
of the Vedalia for the Cottony Cushion Scale, and in this case an un- 
qualified success resulted. On the other hand, the attempt to establish 
the Chinese Lady Beetle in this country to control the San Jose Scale 
has thus far been a failure, and the introduction of the parasite Scutel- 
lista cyanea Motsch. to work on the Black Scale cannot be regarded as 
more than partially effective. 

The danger of introducing along with the parasite, its own parasites 
(secondary parasites) at such a time is great, and therefore this work 
should be attempted only by those especially trained for it. 

All in all, the "bug vs. bug" idea is one which, though always having 
many possibilities of success, is also one which will often fail, and there- 
for cannot be relied upon as a certain panacea for troubles caused by 
introduced pests. 



CHAPTER XXVII 
THE NEUROPTERA 

The insects placed in this group, though quite similar in structure, 
differ markedly in appearance in many cases. They vary much in size, 
ranging from less than a quarter of an inch to several inches in length, 
and their wings may be small or large. 

The mouth parts are for chewing or biting, and most of the group 
feed upon insects and other small animals. The wings are four in num- 
ber, well supplied with both longitudinal and (with a few exceptions) 
cross-veins. The larvae in general are active, moving about in search 
of their prey. A few though, live in the egg sacs of spiders, feeding on 
the young spiders, and in one or two cases, fresh-water sponges appear 
to be their food. There is a quiet pupa stage. 

The group may be characterized as: 

Insects which when adult have two pairs of wings usually large as com- 
pared with the body and ivith numerous longitudinal and {in most cases) 
cross-neins. Alouth parts for cheiving. Metamorphosis complete. 

So far as is known, none of the Neuroptera are injurious insects and 
some at least are decidedly beneficial. About half a dozen families are 
usually recognized and some of these are here considered, either because 
of their economic importance or because they are large and common 
enough to frequently attract attention. 

In the family Sialidae belongs the largest member of the order (Fig. 
217) found in the United States. This is commonly called the Corydalis 
or Hellgrammite (Corydalis cornuta L.) which is quite common throughout 
the country except in arid regions. The mandibles of the male are 
nearly an inch long, slender and somewhat curved; those of the female 
are short. The distance from tip to tip of the wings when these are 
extended, may be over five inches, and the size of the insect and the long 
jaws of the male have led to the mistaken belief that this really harmless 
animal is dangerous. The egg are laid in large masses on objects which 
hang over the water, into which the larvae enter on hatching, making 
their way under stones where they feed for nearly 3 years on the nymphs 
of May-flies, and other insects. Here they are searched for by fishermen 
to use as bait, and are usually called "Dobsons." When full-grown the 
larva makes a cell under some stone close to the stream arid pupates 
for about a month, after which the adult escapes . 

221 



222 APPLIED ENTOMOLOGY 

Smaller species, some with gray, black, or black wings spotted with 
white, belong here. They are often quite common around streams and 
ponds during the summer months and are frequently called "Fish-fiies." 





Fig. 217. — Adult C'orydalis, iibout natural size and its larva. (From Sanderson and 
Jackson, Elementary Entmoloyy; after Comstock.) 

The members of the family Chrysopidae are of great economic im- 
portance as the larvae feed freely on injurious insects, particularly aphids, 
and are so voracious that they are often called Aphis-lions. The adults 
(Fig. 218) are rather small, slender-bodied insects averaging less than an 




Fig. 218. — Adult Lacewing (Chrysopa plorabunda Fitfh), slightly reduced. (From Fnlsom.) 

inch long, with long antennae and large, finely- veined, green wings, which 
when not in use are carried sloping over the body. These adults are 
sometimes called "Golden-eyes" because of their shining, golden-yellow 
eyes, but perhaps more frequently "Lace-wings" from the delicacy and 
beauty of these structures. 



THE NEUROPTERA 223 

The Lace-wings are found practically everywhere in this country 
and are usually quite abundant. They lay their eggs on the stems, 
branches, and leaves of plants, first constructing a slender but quite stiff 
stalk of silk about half an inch long, to the end of which the egg itself is 
attached (Fig. 219). These eggs are usually placed in groups and it is 
believed that were the eggs not raised on stalks out of roach, the first 
larva to hatch would at once proceed to eat the eggs as its first meal. 




Fig. 219. — Eggs of a Lacewing, greatly enlarged. {From Sandcraon and Jackson, 
Elementary Entmolo(jy; after S. G. Hunter.) 



These larvge are rather short, somewhat oval in outline, and have long 
mandibles with which they grasp their prey. The lower side of each 
mandible is grooved and the maxilla of the same side is so modified as to 
fit into this groove and convert it into a tube. An insect attacked by an 
Aphis-lion is seized by the tips of the jaws and its blood is drawn through 
the tubes into the body of its captor. 

Aphis-lions are often found in colonies of plant lic*e which have by their 
feeding caused leaves to curl, and with an abundant food supply thus 
provided, the insect is both protected by the leaf and insured of the food 
it needs for its development. 

When full-grown the Aphis-lion forms around its body a white, shin- 
ing, spherical silken cocoon in which it pupates. When this process is 
complete the adult cuts out a circular piece of the cocoon, forming a hole 
through which it escapes. 

The importance of Lace-wings as friends of man is such that they 
should be protected and not destroyed under the impression that being 
9,mong known pests they must also be for that reason injurious. 



224 



APPLIED ENTOMOLOGY 



In the Western States are a few insects belonging to the Neuroptera, and 
family Raphidiidae. They are small, less than an inch in length, but with an 
unusually long prothorax (Fig. 220). The larvae feed on other insects and, 
among others, on codling moth larvae. They occur chiefly under loose bark in 
this stage, and while not as abundant as could be desired, do good work by attack- 
ing many injurious species. They have been introduced into AustraUa in the 
hope that they may become effective enemies of the codling moth there. 





Fig. 220. Fig. 221. 

Fig. 220. — Adult Raphidian {Raphidia oblita Hagen), about twice natural size. 
{Original.) 

Fig. 221. — Adult Mantispa {Mantispa brunnsa Say) showing grasping front legs. 
Somewhat enlarged. {Original.) 

Another family, the Mantispidae, though few in numbers, has its members 
quite widely distributed. The Mantispas (Fig. 221) as they are called, like the 
Raphidians, have a greatly elongated prothorax and their fore legs are also long 
and adapted to grasping their prey. The adults are larger than the Raphidians, 
being about an inch in length and with long wings. Though feeding on other 
insects, most of which are likely to be injurious, the Mantispas are not numerous 
enough to be of any great importance. 





Fig. 222. 
Fig. 222. — Adult Ant-lion about natural size. {Original.) 
Fig. 22.3. — Larva of an Ant-lion, about twice natural size. 



Fig. 223. 



{After Meinert.) 



The insects belonging to the Family Myrmeleonidae are generally 
spoken of as the Ant-lions, though the name "Doodle-bug" is sometimes 
applied to their larvae. They are widely distributed over the United 
States, particularly in sandy places, but are most abundant in the South. 



THE NEUROPTERA 225 

Many kinds of the adults (Fig. 222) superficially greatly resemble the 
"damsel-fiy" section of the Dragon-flies (Odonata), their long, slender 
bodies, large, gauzy wings and their general size causing the resemblance. 
Their antennae, however, instead of being very small and not noticeable, 
are of fair size and knobbed at the tip, which provides an easy way by 
which to distinguish the two groups. Other characters and their life 
history also prove that the resemblance is only superficial. 

The larvae of the ant-lions (Fig. 223) greatly resemble those of the 
lace- wings in general form and in the possession of long jaws grooved for 
sucking the blood of their victims. They excavate little conical pits 
in soft, dry, preferably sandy ground, an inch or two across and as deep 
as possible for the sandy sides to hold. At the bottom of the pit thus dug 
the young ant-lion buries itself except for its head, and waits for an 
unwary insect to fall in. Sliding down the slope of loose earth the victim 
literally falls into the jaws of the waiting enemy and is killed and de- 
voured. It has been stated that sometimes the insect on its way down 
the side of the pit is able to check itself and start to climb out, and that 
then the ant-lion shovels a load of sand onto the top of its flat head, with 
its leg, and snaps the sand up the side of the pit, where falling, it sweeps 
the prey down to the bottom within reach of the ant-lion! 

The process of excavating the pit is also one of extreme interest. 
The insect first traces out a circle of the desired size, loading its head with 
sand from inside the circle and snapping it out, and on completing the 
circle, repeats the process but in the reverse direction, and this is continued 
until the pit has been completed. In doing this the larva always moves 
backward. 

After becoming full-grown the ant-lion larva forms a spherical cocoon 
of sand and silk in the ground, within which it transforms to the adult. 

The ant-lions, though feeding on other insects, are of little if any 
economic importance as the forms they are most liable to capture are not 
often probably, serious pests. Their habits and manner of life, how- 
ever, are so interesting that much attention has been given to them and 
what has been published about them forms one of the most interesting 
chapters of Entomology. 

The Neuroptera, though widely distributed over the world, do not 
constitute a large group. Less than two hundred kinds are known in 
this country, and probably not more than a thousand kinds in all have 
thus far been discovered. Fossil specimens of several of the families have 
been recognized. 



CHAPTER XXVIII 

THE TRICHOPTERA 

The Caddice (sometimes spelled Caddis) Flies, as the members of this 
order are usually called, are rather soft-bodied insects ranging in size 
from less than an eighth of an inch to an inch or more in length. 

The wings, though much reduced in a few cases, are almost always 
large and well developed, with numerous longitudinal, but few cross- veins. 
They are membranous, the front pair somewhat leathery, and all are 
more or less densely covered with hairs which in some species are rather 
scale-like in form. The hind wings are usually broader than the front 
pair and when not in use are sometimes folded lengthwise. The position 
of all the wings when at rest is with their hinder margins together over the 
back of the insect and their costas down at the sides of the body, upper 
faces sloping downward and outward like a house roof (Fig. 224). 

The mouth parts of the adult are poorly developed though evidently 
modified from the chewing type and it is probable that little if any food is 
taken in this stage. The antennae are generally well developed, and in 
some species they may be several times as long as the body. The legs 
are quite long and slender. 

The larvae (Fig. 225) somewhat resemble small caterpillars in form. 
They are nearly all found in water, chiefly that of ponds or slow-running 
streams, though a few inhabit rapid currents. The abdomen is soft, the 
chitinous skin being delicate, and the larvae therefore construct cases of 
various materials as a protection for this portion of the body. 
The Trichoptera may be defined as : 

Insects which as adults have rather soft bodies: four membranous wings 
with numerous longitudinal and few cross-veins, and more or less closely 
covered by hairs, folded over the body like a house roof when at rest: mouth 
parts rather rudimentary: antennce and legs quite long, the former sometimes 
exceptionally so. Larvce living in cases, nearly always in the water. Meta- 
morphosis complete. 

The adult Caddice-fly, though having well-developed wings, is not a 
strong flier and these insects are therefore most frequently found near 
water. 

The eggs are, at least usually, laid in clusters in a mass of jelly, and 
are probably dropped into the water. On hatching, the larvae begin the 
construction of cases in which to live. The materials of which these are 

226 



THE TRICHOPTERA 



227 



made differ according to the species of Caddice-fly concerned and vary- 
greatly (Fig. 226). Some take pieces of leaves which have fallen into the 
water; others select veins of the leaves and similar sized straws and put 
them together cris-cross, something like the logs of a log house; some 
species use the finest sand for this purpose; 
others coarse gravel, and still others use a mix- 
ture of long and short pieces of plants so that 
the ends of the longer ones extend some distance 
behind the end of the case. 

The case itself is usually straight but in some 
species it may be curled, and resembles a small 
snail-shell. Indeed this resemblance is so close 
that in one instance at least, such a case was 
actually described as that of a shell! The ma- 
terials, whatever they may be, are held together 
by silk spun by the larva, coming from silk glands 
within the body and poured out through an 
opening close to the mouth. Within the case 
the larva lives, crawling about by extending its 




Fig. 224. — Caddice-flies: adult at rest, above; with wings spread, below. Larvae showing 
three kinds of rases, crawling. (From Linville and Kelly, General Zoology.) 



head and thorax out of the front end so that its feet can be used, and 
dragging the case along. 

Some caddice-fly larvse make simpler houses than these. Such species 
live in rapid water and there fasten a few tiny stones under rocks by their 



228 



APPLIED ENTOMOLOGY 



silk, and between these spin a silken tube in which to live. Close to this 
they spin more or less funnel-shaped webs, the mouth up-stream and so 
arranged that tiny animals swept down by the current within the outer 
limits of the funnel come within reach of the larva lying in its tube. 
While the food of these larvae is carnivorous, in most of the species plant 
materials are consumed. 

The larvae, in most cases, breathe by tracheal gills which are slender 
filaments, frequently grouped in clusters, and attached to the abdominal 
segments. Other structures present in some species are also suspected of 
being concerned with respiration. 




Fig. 225. Fig. 226. 

Fig. 225. — Caddice-fly larvae: larva with head and thorax extended out of its case, 
above; larva removed from its case, below, showing tracheal gills. About twice natural 
size. {Modified from Leuckart's Wandtafeln.) 

Fig. 226. — Examples of different types of cases formed by Caddice-fly larvse. {From 
Sanderson and Jackson, Elementary Entomology: after Furneaux.) 

When full-grown the Caddice-worm forms a sort of lid or door grating 
across the front opening of its case, though not complete enough to pre- 
vent water from entering and supplying the insect with the oxygen it 
needs. After pupation in its case the adult swims to the surface and 
grasps some object, from which it takes its flight. In some species it is 
apparently the pupa which when ready to become the adult, comes 
to the surface and passes its final molt there. 

The Trichoptera is quite a large group of insects and representatives 
of it are found in almost all parts of the world. Probably not many more 
than a thousand species have been described, as they do not appear to be 
of any economic importance unless their consumption of decaying vege- 
table matter in pools can be considered as desirable, but it is very likely 
that there are from five to ten thousand kinds in existence. Their cases 
have been found as fossils and adults have also been preserved in this way. 



THE TRICHOPTERA 229 

The Trichoptera are evidently closely related to the Lepidoptera in 
many ways and are undoubtedly with the last-named order, divergent 
descendants from common ancestors. Some Lepidoptera so closely resem- 
ble Trichoptera in fact, that they have been placed in the latter group. 
They also have many resemblances to the Neuroptera, but their connec- 
tion with this order is plainly more remote, and sufficient time has elapsed 
since the divergence of the present Neuroptera and Trichoptera from their 
common ancestors, to permit the development of many differences. 



CHAPTER XXIX 



THE LEPIDOPTERA 



The Lepidoptera are the moths and butterflies, which form one of 
the largest and most noticeable groups of insects. Its members are 
found in all countries and their large size in many cases, their brilliant 
colors and the habits of their larvae as well as the injuries they cause, 
have attracted much attention. 

The adults have four, large, membranous wings in most cases (a few 
have lost their wings), more or less completely covered by overlapping 
scales making the wings opaque where these are present. Colors of the 

wings are due either to the presence of 
pigments in the scales: to optical colors 
caused by the surfaces of the scales break- 
ing up the light striking them; or by both 
factors together. 

The mouth parts of the adult are greatly 
modified from those of chewing insects, 
though enough remains to show that the 
ancestors of the group must have fed by 
chewing. The development of the parts 
varies in different species, some of the 
lower forms having as a whole, a much 
closer resemblance to the condition in 
chewing insects than is the case with most 
of them. In one group, the mouth parts 
are sufficiently of the mandibulate type to 
enable the insects to feed on pollen. 

In general a labrum or front lip is evi- 
dent, but the mandibles are practically lost. 
The maxillae are extremely modified, a por- 
tion of each contributing its half to the formation of a proboscis or tongue 
(Fig. 227). This is a flexible oi'gan varying greatly in length, its two 
halves so interlocking as to form a tube between them, through which, 
when completely developed, fluids may be drawn into the mouth. The 
degree of development of the proboscis differs greatly in different 
Lepidoptera, and while it is functional in perhaps the majority of the 
group it is only partly developed or even rudimentary and useless in 
others. Such Lepidoptera evidently do not feed while adult. 

230 




Fig. 227. — Diagram of head of 
a Lepidopterous insect, showing 
the tongue. (From a drawing by 
M. F. Webster.) 



THE LEPIDOPTERA 231 

In some cases the maxillary palpus is developed : in others it is nearly 
or wholly lacking. The labium or hinder lip is also practically absent 
except for the labial palpi which are usually large, thickly covered by 
hairs or scales, and project forward at the sides of the head, often 
turning upward somewhat, and partially or wholly concealing the pro- 
boscis when this is coiled up under the head, the place where it is carried 
when not in use. 

The mouth parts of the larva (or caterpillar as it is usually called) 
are entirely different. In this stage they are chewing structures, similar 
to those of a grasshopper in a general way, and no special description is 
needed. In the center of the end of the labium, however, is a slender 
projection called the spinneret, which at its tip has the external opening 
of the duct leading to the silk glands. 

The antennae of adult Lepidoptera are usually quite long but vary 
greatly in their form in different species. In the butterflies they are 
slender but enlarged near the tip forming a club (Figs. 309 to 317), or 
with this enlarged part bent into a sort of hook (Fig. 308). These forms 
of antennae are almost never found in the moths, where they may be 
simple and thread-like; with small hair-like projections at the side; 
bristles in place of the hairs; clusters of the bristles; with tooth-like or 
saw-like side projections; with long projections on one or both sides, in 
the latter case giving the antennae a feather-like appearance; and other 
forms also occur. (Compare Figs. 228 to 305). 

The eyes are large, though in some cases partly concealed by hairs 
or scales, which as a rule thickly clothe the entire body. Ocelli are also 
sometimes present. On the top of the prothorax a pair of projections or 
lobes often occurs, called patagise, sometimes very large and capable of 
some movement; in others, smaller or even reduced to mere traces. On 
the large mesothorax is a somewhat similar pair of structures called the 
tegulse which extend backward over the point where each fore wing 
articulates with the body. The abdomen may be long or short, stout 
or slender, connected with the thorax either by a broad or a rather 
constricted attachment. The legs are quite long and slender. 

Characters by which the members of this group may be distinguished 
are: 

Insects which as adults have (with a few exceptions) four membranous 
wings more or less completely covered by overlapping scales: mouth parts 
for Slicking. The larvce have chewing mouth parts. Metamorphosis 
complete. 

The Lepidoptera is such a large order that great differences in its 
members are very common. The smallest ones are almost microscopic 
while the largest one known may measure about a foot between the tips 
of its expanded wings. The wings of each side, to obtain their greatest 
efficiency, are more or less completely coordinated for flight by one 



232 APPLIED ENTOMOLOGY 

of three methods. In the butterflies and some of the moths, the basal 
portion of the costal region of the hind wing is enlarged, forming a sort 
of shoulder over which the hind margin of the fore wing lies, thus enabling 
the two to a large extent, to function as a single wing. In most moths, 
however, instead of a shoulder, a rather long, curved bristle or cluster of 
bristles, called a frenulum, arises near the base of the hind wing and runs 
forward and outward, passing under a small flap or through a tuft of 
scales on the under side of the fore wing, so that as the two wings move in 
flight, this frenulum slides backward and forward in its track under the 
fore wing and holds the two together. A third type of connection, found 
in only a few moths, is a small lobe near the base of the hind margin of 
the fore wing, which extends backward toward the hind wing. This lobe 
is called a jugum and is also probably more or less effective in producing 
coordination in the use of the wings. 

The number and arrangement of the wing veins is of great importance 
in the Lepidoptera, much of the classification in this order being based 
upon these structures. The main veins (see Fig. 20) are of course, 
longitudinal, starting at the point of attachment of the wing to the body 
and diverging toward its outer margin, some of them branching several 
times. Cross-veins are very few, however, and consequently there are 
only a few closed cells (see page 13), and some at least (perhaps all) 
of these are produced by the fusion of branches of longitudinal veins, 
rather than by true cross-veins. 

Various ways of designating the veins and their branches have been 
offered, but these are best comprehended in connection with laboratory 
work on the insects themselves, and are therefore not given here. 

The eggs of Lepidoptera vary greatly in form and also in color. 
They may be elongate, spherical, flattened, scale-like, or of other forms, 
and the shell or chorion may be smooth or sculptured with ridges and 
reticulations. The eggs may be laid singly or in clusters and may or 
may not be covered with hairs from the body of the parent moth, or 
with a secretion which conceals them from view. They may hatch in 
a few days or after longer periods, in some cases many months. The 
adults have no ovipositor so the eggs are always laid on the surface 
of the place of deposition, though if the abdomen of the insect be small, 
this may be in a small crack or other opening. 

The larvae produced by the hatching of the eggs are called cater- 
pillars and have no resemblance whatever to the adults they are to 
become. They are usually rather worm-like animals, with a generally 
recognizable head and a body consisting of a series of rather similar seg- 
ments, the first three of which correspond to the thorax of the adult and 
almost always bear six legs. Some of the following segments will also 
have legs but these are totally different in structure from the others and 
are merely temporary in their nature, designed to support this portion of 
the body. 



THE LEPIDOPTERA 233 

The internal structures of the caterpillar do not differ greatly in their 
arrangement from those of an adult insect, except that the reproductive 
organs are only slightly developed at this time, and in the presence 
along each side of the body of a silk gland, large in those which will 
later need large quantities of silk, but present in all. A duct from each 
gland runs forward to the mouth where the two unite and open to the 
exterior through the spinneret already referred to. 

Most caterpillars feed on plants or vegetable material. Their work 
is noticed chiefly by their stripping plants of their leaves, though some 
bore in stems, roots, fruit, seeds or other parts. A few attack feathers, 
silk, etc., but this is not the general habit. The larval stage may last 
only a few days for some species but is generally a month or more, and 
some feed during the fall, become quiet during the winter, and complete 
their feeding the following spring. 

A large majority of the caterpillars are termed naked, having only 
a few tiny spines or hairs, not large enough to be noticeable. From 
this condition every grade of density of covering occurs, to species entirely 
covered by long, thickly placed hairs which give the animal a hairy or 
" woolly " appearance. Some have large warts or horns on the thorax or a 
sort of horn above, near the hinder end of the body. 

Their colors also vary greatly, some being brightly colored while 
others, green, either with or without white streaks, appear to seek con- 
cealment by their resemblance to the leaves on which they feed. Those 
living in protected situations, such as in plant stalks, are nearly white: 
cutworms which pass the day in the ground are dark as a rule, with 
rather faint markings. 

When the caterpillar has become full-grown it generally leaves the 
place where it was feeding and in some satisfactory location, spins a 
cocoon around itself, using for this purpose the silk produced by its 
silk glands. In some species the cocoon is very complete, thick, tough, 
and entirely conceals the larva within. On the other hand, there are 
cocoons where only sufficient silk is used to attach the insect and hold it 
in place; and between these extremes all degrees of cocoon construction 
occur. Sometimes leaves, hairs from the body of the caterpillar, or dirt 
when the insect enters the ground at this stage, are incorporated in the 
cocoon. 

Within the cocoon the caterpillar molts, leaving its cast-off skin at 
one end. The result of this molt is a pupa, its form showing through 
its new skin which is generally brown, the outlines of the adult body 
and its appendages including the wings being evident, these last, however, 
very small as there would be no room for the full-sized wings of the adult 
within the cocoon. Internal changes and the completion of such external 
ones as are necessary, now proceed until the adult insect has been entirely 
formed, and is ready to escape. When this happens another molt re- 



234 APPLIED ENTOMOLOGY 

leases the insect from the brown outer pupa skin, and either before or 
after this, an opening in the cocoon is made and the adult emerges. 
It then crawls up on something and remains quiet for a while; its wings 
being free to expand, increase rapidly till of their full size; the surplus 
fluids in the body are expelled, and after an hour or two the insect is 
ready for flight. 

While for most Lepidoptera this outline of development is in general 
correct, in the butterflies we find that cocoon making is limited to attach- 
ing the hinder end of the body by silk, to the object on which it is to 
pupate, and the formation of a silken loop around its body to hold it up. 
Such a pupa, producing a butterfly, is usually given the special name 
"chrysalis." (See Fig. 317/). 

Besides the names "butterflies" (Rhopalocera), and "moths" 
(Heterocera) used to distinguish different sections of the Lepidoptera, 
we also have the terms "Microlepidoptera" or small moths, and "Macro- 
lepidoptera" or large ones. These are wholly relative and rather indefi- 
nite, but are nevertheless convenient in spite of the fact that it would be 
doubtful under which head to designate many species of the order. 

The latest list of the insects of this order found in North America 
places them in about 70 families, but there are more of these divi- 
sions in other parts of the world. Some of the families include many 
species and insects of much economic importance, while others have 
only a very few. Only the more important families, either in size or 
because of the pests they contain, are included here. 

Family Cossidae (Carpenter Moths). — The larvse of the moths belonging in 
this family bore in trees and are sometimes quite injurious. There are several 
native species, the most common being the Carpenter Worm or Goat Moth 
(Prionoxystus rohinice Peck) which lays its eggs in the crevices of the bark of 
various trees. The larvse bore in the limbs injuring or killing them, and the 
entire life history is beUeved to take 3 years. The adults which appear in June 
and July are quite large, the wings of the female spreading about three, and those 
of the male about two inches. The wings are mottled light and dark gray, except 
the hind wings of the male which are yellow. The Leopard Moth ( Zeuzera 
pyrina L.), a European pest belonging in this family, reached this country before 
1879 and now occurs along the Atlantic Coast from New Hampshire to Delaware 
and a rather short distance inland. The wings of the moths (Fig. 228) spread from 
one to about two inches and are white with numerous black spots. The thorax 
has seven black spots above. The moths appear from May till September and lay 
their eggs on the bark, several hundred in all, but usually only a few at a place. 
The caterpillars (Fig. 229) are liable to enter the small twigs, but may enter else- 
where, and bore through the wood. Small twigs are killed and larger ones weak- 
ened and in time may also be destroyed by this boring, and if the branch becomes 
too small at any time for the larva, it will leave it for a larger one. Injured 
Umbs are often so weakened as to break off during storms. The borer feeds during 
parts of three seasons, pupating in its burrow the third spring. It is more 
abundant in and near cities and towns than in the open country 



THE LEPIDOPTERA 



235 



The work of borers of this group is often evidenced by fine chips, excrement 
or frass pushed out of the entrances to the tunnels; by wilted leaves; by tunnels 



i 










..^\ 



K^' 






Fig. 22<S. — Adult female (left) and male (right) of the Leopard Moth (Zciizcra pyrina h.) 
about natural size. {From Britton, Eleventh RepL Ent. Conn. Agr. Exp. Sta. 1911.) 




Fig. 229. — I>arva of Leopard Moth in its burrow. Natural size. {From Britton, Elevenlh 
Rept. Ent. Conn. Agr. E.rp. Sta. 1911.) 

in fallen branches, and by splits and breaks in the bark when the larvse work just 
beneath it. 



236 APPLIED ENTOMOLOGY 

Control for the Leopard Moth and for Carpenter Moths in general is to locate 
the entrance holes of the larvae and inject a little carbon disulfid into them, then 
stopping the opening with putty, mud or wax. Thoroughly infested trees should 
be cut and burned during the cold months, to destroy the caterpillars in them, 
as such trees are doomed in any case. 

Family Tineidae (Tineids). — The insects belonging in this family- 
are all Microlepidoptera, the distance between the tips of their wings 
when spread being generally much less than an inch. They are not 
noticeable insects and only a few are of great importance. Three, 
however, are serious household pests and cause much injury, being the 
species commonly called Clothes Moths, all natives of Europe but for 
many years now, present in this country. 

The Case-making Clothes Moth (Tinea pellionella L.). — This is the 
most generally distributed of the three species and is the most common 
one in the North. The moth flies at night and may frequently be seen in 





Fig. 230. Fiu. 231. 

Fig. 230. — Adult of Case-making Clothes Moth {Tinea pellionella L.) four times natural 
size. (From Herrick's Insects Injurious to the Household. By Permission of the Macmillan 
Company, Publishers.) 

Fig. 231. — Case of the Case-making Clothes Moth, three times natural size. {From 
Herrick's Insects Injurious to the Household. By Permission of the Macmillan Company, 
Publishers.) 

infested houses flying about the rooms but not attracted to any light 
there may be present. In fact, if during June, July or August any tiny 
moth flies to the light in a room at night, that fact is of itself evidence that 
the insect is not a clothes moth. 

The adult (Fig. 230) is grayish-yellow with faint spots, its hind wings 
more nearly a silvery gray. It spreads about half an inch. The eggs are 
generally laid on woolen goods of any kind, furs or feathers. They 
hatch in about 10 days and each larva constructs a case (Fig. 231) made of 
particles of the materials on which it feeds, lined with silk, and with its 
body in the case, crawls about, feeding as it goes. As it grows and the 
case becomes too small, the caterpillar enlarges it and when full-grown 
attaches it to some object and pupates in it, the moth emerging about 
3 weeks later. In the North there usually seems to be but one generation 
a year but in the South there are two and possibly more. 

The Webbing Clothes Moth (Tineola hiseUiella Hum.). — This species, 
though found in the North, is most common in the South. The adult 



THE LEPIDOPTERA 237 

(Fig. 232) is of about the same size as that of the last-described species, 
but its fore wings are uniformly yellowish. There are two generations 
each year. The caterpillar feeds on the same materials as that of the 
Case-making Clothes Moth and has also been known to eat cobwebs, 
dried specimens of insects and beef meal. It does not form a case but 
spins a sort of web of silk as it moves about. When ready to pupate 
it forms a cocoon of silk to which particles of wool or whatever it has been 
feeding on, are added. 





Fig. 232. Fig. 233. 

Fig. 232. — Adult, of the Webbing Clothes Moth (Tineola biselliella Hum.), four times 
natural size. {From Herrick's Insects Injurious to the Household. By Permission of the. 
Macm,illan Company, Publishers.) 

Fig. 233. — Adult of the Tapestry Moth (Trichophaga tapetzella L.), three times natural 
size. {From, Herrick's Insects Injurious to the Household. By Perm,ission oj the Alacmillan 
Company, Publishers.) 

The Tapestry Moth (Trichophaga tapetzella L.). — The Tapestry Moth 
is not as common in this country as the other two clothes moths, and is 
a larger insect (Fig. 233), spreading about three-quarters of an inch. It 
seems to prefer to attack heavier and coarser cloths than the other species, 
as well as felts, skins, etc., and is found in carriage upholstering and similar 
places, as often as in houses. The caterpillar tunnels in its food, lining 
the galleries somewhat with silk, and in these galleries it also pupates. 

Control for Clothes Moths. — All woolen goods, furs, feathers, rugs and 
similar materials not in regular use during the summer should be care- 
fully aired in the sun as long as possible, and brushed, beaten or shaken 
thoroughly before being put away in the spring. • They should then be 
placed in tight trunks, boxes or bags either of cloth or paper. After 
being thus treated they should be safe for the summer, provided no 
eggs nor larvae have escaped and are still present in the materials. But 
a surer method is to thoroughly fumigate the articles when they are 
packed away, using carbon disulfid. Thus an ordinary trunk filled with 
such articles can be fumigated for from 24 to 48 hr., then opened and a 
liberal supply of moth balls (naphthaline) or flake naphthaline be added 
and the trunk finally closed. 

Repellents are of some value to keep clothes moths away from 
materials liable to injury, but their value is largely dependent upon the 
amount used and on whether the insects are already present. It appears 
that while clothes moths will not usually, at least, lay their eggs on 
materials stored with an abundant supply of naphthaline, this substance 



238 APPLIED ENTOMOLOGY 

in any such amounts as are usually added will not keep eggs already 
present from hatching, nor the larvae from feeding. Therefore, fumiga- 
tion first, to kill any of these insects which may be present in any stage, 
followed by an abundant supply of naphthaline to keep them away 
thereafter would seem to be the best method of procedure. 

Other repellents often used are cedar-wood chests, sprigs or chips of 
cedar, camphor, tarred paper, and tobacco. They are all repellents, 
but apparently less effective than naphthaline. In the case of cedar it 
is the oil present which gives the protection, and as this is volatile it is 
lost after a time and then a cedar chest is of no more value for storage 
than one of any other kind of wood. 

Closets often become infested by clothes moths and even after taking 
out and treating the clothing the moths may appear. It is probable 
that in such cases the larvse find particles of wool or other edible materials 
in the cracks of the floor or elsewhere on which to live. In such cases the 
free use of gasoline or kerosene on the walls and floors, paying particular 
attention to all cracks, followed after a few hours by a thorough airing, 
should give relief. If not, fumigation of the closet^ being careful that 
cracks around the doors or other openings are tightly sealed, will 
exterminate the insects there. 

Rugs and carpets infested should be thoroughly cleaned and can 
then either be baked to 125°F.; fumigated as above, or sprayed with 
benzine. Furniture attacked may be saturated with benzine or fumi- 
gated. Where an entire house is infested, no one place apparently 
more than another, fumigating with hydrocyanic acid gas at the rate 
of 1 oz. of sodium cyanid to every 100 cu. ft. of space has given good 
results. 

Rugs, furs and woolens valuable enough to place in cold storage 
may be protected during the summer by cold. It has been found that 
exposing infested goods to very low temperatures for a few days, followed 
by another short period in a fairly warm place, then returning tbem to the 
cold room for a short time will kill the insects present, these being unable 
to live through such severe temperature changes. After this the articles 
can be stored during the rest of the season in a temperature of about 40°F. 
with safety. 

Family Eucosmidae. — In this family are a number of pests of fruit 
trees and other plants. All of them are small moths, rarely spreading 
over three-quarters of an inch. One of the worst pests of the apple — the 
apple-worm or codling moth — belongs here. 

The Codling-moth {Laspeyresia pomonella L.). — This pest of apples, 
pears and occasionally of other fruits is a native of Southeastern Europe 
but is now found almost every where and is present in all the apple-growing 
sections of this country. 



THE LEPIDOPTERA 



239 



The adult moth (Fig. 234) has its fore- wings brown, crossed by irreg- 
ular gray and brown lines. It spreads about three-quarters of an inch 
and is not often seen as it flies only at night and is not attracted by lights. 

Winter is passed in the full-grown caterpillar stage in some protected 
place, usually under a piece of bark of the tree where the insect fed (Fig. 
235). Under the bark the caterpillar digs out 
an oval cavity and lines it with silk in which to 
winter. In the spring it pupates here and the 
adult moth escapes a week or two after the 
petals fall at the blossoming season in the 





Fig. 234. Fig. 235. 

Fig. 234. — Adult Codling Moth {Laspcyrcsia pomonella L.), twice natural size. 
{Original.) 

Fig. 235. — Piece of bark showing Codling Moth cocoons and pupse on its under 
surface. About one-third less than natural size. {Modified from Cornell Agr. Exp. Sta. 
Bull. 142.) 

spring. Tiny, white, flattened eggs, 50 to 75 in number, are now laid 
singly on leaves, twigs or on the small fruit, but mainly on the leaves. 
The eggs hatch in about a week and the little caterpillars feed for a short 
time on the foliage, but soon leave this and crawl to the fruit, where froni 
60 to 80 per cent enter at the blossom end, often burrowing their way 
through between the closed calyx lobes or sepals to reach the cup-shaped 
cavity within. From the bottom of this cavity they tunnel into the fruit 
to the core, in and around which they 
feed until full-grown; a period of 
nearly a month in most cases. The 
other 20 to 40 per cent enter the fruit 
at any point, but appear to prefer a 
place where a leaf or some other 
object lies against the fruit. 

When its growth has been com- 
pleted the caterpillar (Fig. 236) is 
about three-quarters of an inch long, 

pinkish or whitish, with its head and a patch above, just behind the head, 
and another at the hinder end of the body, brown. It now leaves the 
fruit, generally burrowing out through the side and makes its way down 
the tree until it finds some piece of bark loose enough to permit it to 
gnaw its way under, and here it forms an oval cavity as already 
described. 




Fig. 236. — Full-grown larva of Codling 
Moth, about twice natural size. (Modi- 
fied from Cornell Agr. Exp. Sta. Bull. 142.) 



240 APPLIED ENTOMOLOGY 

Over the greater part of the United States there are two generations 
of the Codhng-moth each year. Where this is the case the larva pupates 
in this cavity for about 2 weeks before it escapes as an adult. Eggs are 
now laid for the second generation and on hatching the larvse attack the 
fruit, which is quite well grown by this time, entering it at any point and 
showing no preference for the blossom end. The feeding of this genera- 
tion of caterpillars proceeds as with the spring generation, but in many 
cases has not been completed when the fruit is gathered. In this way 
a number of the larvae may be carried to the bins or barrels in which the 
fruit is stored. Later, they leave the fruit and make their wintering 
cases on the sides of the bins or elsewhere. 

In the Northern States there is only a partial second generation, 
most of the caterpillars feeding during late June and July, failing to 
transform into moths that season, so that the work of the insects in fruit 
during the fall is comparatively unimportant. From Southern New 
England south, however, two complete generations are the rule and in the 
more southern States with long growing seasons, there may be three gener- 
ations. In the West, even as far north as Washington, two generations 
occur. Cold and drought have a considerable effect everywhere, how- 
ever, late springs reducing the number of moths which appear the same 
season. 

The injury caused by this insect places it among our most important 
pests. Small apples attacked, drop in many cases, resulting in the entire 
loss of some of the fruit early in the season. In years of an abundant 
crop, this is of less importance, but in "off years" it is a serious matter. 
Fruit infested which remains upon the tree is reduced in value and thus 
another loss is produced. It has been estimated that a few years ago 
the State of New York alone lost apples and pears forming a third of the 
entire crop, which valued at $1.50 per barrel, would amount to about 
$3,000,000 per year. 

Control. — There appear to be two chief ways by which the habits of 
this insect aid in control measures. The number which enter the fruit 
at its blossom end is large, and poison placed there for them to eat as they 
bore their way through it into the apple, has proved effective. The fact 
that the caterpillars feed for a time on the leaves before going to the fruit 
also indicates a place for successful treatment. 

Accordingly, spraying with arsenate of lead, standard formula, within 
10 days after the petals fall, directing the spray so that as far as possible 
it will fall into the cup surrounded by the calyx lobes (sepals) is the most 
usual method of control. In applying this spray, however, it should be 
remembered that in the case of the apple these calyx lobes which at first 
stand widely open around the edges of the cup, soon draw together and 
close up the cup mouth, after which no spray can be placed where it is of 
use (Fig. 237). This closing comes about 10 days after the petals fall 



THE LEPIDOPTERA 



241 



(Fig. 238) and thus limits the effective spray period to that time. For- 
tunately, different varieties of apples do not bloom at quite the same time, 
so that spraying where large orchards are involved should begin with those 



d^ii 


M^ 


w^m 


Hh|L^J||k 


m 


^^^V«' !» -^^^^^m C^^^^M. 


-■-'^ 


W'W^m 


^ 


[^ V^r^^L^H * 


_^^ 




m 





Fig. 237. — Apple blossoms in proper condition for receiving the calyx spray. Adult 
Codling Moth, natural size, above. {From Felt, 27th. Rept. N. Y. Slate Ent., 1911.) 

trees which lose their petals first, taking the later-blooming varieties 
afterwards. When the sepals close this helps to hold the poison in the 
cup ready to be consumed whenever the caterpillars reach it. Where 




Fig. 238. — Small apple showing calyx lobes practically closed. Too late for successful 
spraying. {Modified from Cornell Agr. Exp. Sta. Bull. 142.) 

pears are to be sprayed, their treatment can be postponed until the work 
on the apples has been completed, as in the pear the calyx lobes do not 

16 



242 APPLIED ENTOMOLOGY 

close and the spray can be successfully applied more than 10 days after 
the petals fall. 

About 3 weeks after the petals have fallen, or perhaps a few days 
later, a second spray of arsenate of lead, placed upon the leaves, poisons 
these just before the young caterpillars of the Codling-moth hatch and 
begin to feed. Many of these larvae will thus be poisoned before they 
reach the fruit. 

Another application of arsenate of lead 8 or 9 weeks after the petals 
fall will poison the leaves just before the second generation of caterpillars 
begins feeding, which seems to be the chief protection available against 
these insects at this time. 

Minor methods for reducing the numbers of this pest are also made use 
of. Some of the caterpillars may escape death from feeding on the poi- 
soned leaves and in the first, as well as in the second generation, enter the 
fruit through the side. These larvae cannot themselves be reached, but 
the pupae or adults they become, if destroyed, will reduce the number of 
the next generation. To accomplish this all loose bark on the trees is 
removed about the first of July (earlier in the South) and a loose band of 
cloth or burlap is placed around the trunk. The larvae on leaving the 
fruit, seek for a place in which to transform to adults, and finding no bark 
under which to make their cocoons, crawl down the tree till they find the 
band which provides the opportunity they desire, and under which they 
therefore go. Turning over this band frequently during the summer and 
fall and destroying the insects found under it will therefore eliminate 
them from any further consideration. 

Cleaning out bins, barrels and all other places where fruit has been 
stored, early in the spring, destroying all the insects found there is also 
a good practice and is a desirable treatment for the Codling moths 
located in such places. 

In spraying for the codling-moth there has been a considerable 
difference of opinion as to the most successful method. Some western 
workers have advised a rather coarse spray driven with great force, such 
as by a pressure of 200 lb. or more at the pump, just after the petals 
fall, claiming that in this way the spray is driven to the bottom of the 
cup and that later sprayings are unnecessary. Others, mainly in the 
East, have advised a misty spray driven by a pressure of about 100 lb., 
and giving a second (and where there are two full generations a third) 
spray. These opposing views may have an explanation ifi the different 
conditions in apples at the calyx end during and after the closing of the 
calyx lobes in different parts of the country, but in general a compromise 
between the two methods, resulting in the use of a medium spray driven 
with considerable force, followed by the other sprays as they may be 
needed, seems to be the usual practice at the present time. 



THE LEPIDOPTERA 



243 



Family ^geriidae (The Clear-winged Moths). — This family, some- 
times called the Sesiidse, includes a number of moths whose wings are 
only partially covered by scales. They are not large insects, spreading 
on an average, about an inch and are often brilliantly colored. They 
fly during the day and particularly during its warmest portion, and are 
very rapid in their flight. The larvae are whitish in color and are all 
borers, either in stems, roots or under bark. They are therefore, all 
injurious, their importance to man depending on the value of the plant 
attacked. 

The Peach Borer (Synanthedon exitiosa Say). — This insect which is 
a native of North America is a serious pest of the peach wherever these 
trees occur east of the Rocky Mountains. West of this a very closely 
related species, the Pacific Peach Borer (Synanthedon opalescens Hy. 
Edw.) has a similar life history, habits and control methods. 





Fig. 239. — Adult Moths of the Peach Borer {Synayithedon exitiosa Say), twice natural 
size: a, male, b, female. (From Britton, Ninth Rept. Ent. Conn. Agr. Exp. Sta. 1909: after 
Beutenmuller .) 

The adult insect (Fig. 239) is a httle larger than the average, usually 
spreading a little more than an inch. The male has a dark blue body 
and its transparent wings are bordered with blue. In the female the 
fore wings are entirely blue, the hind wings transparent and an orange 
band crosses the blue body at about the middle of the abdomen. The 
moths may often be noticed darting about in peach orchards during the 
middle of the day, anywhere between early May and October (even 
earlier in the Gulf States), but are most abundant during June and July 
in the Southern States, and July and August in the North. The eggs, 
several hundred in number, are laid singly or a few together on the trunk 
of the tree near the ground, and the larvae on hatching bore into the 
sap-wood close to the ground and feed in that region until winter, at 
which time most of them are about one-third grown. In the spring they 
resume their feeding (Fig. 240) and upon reaching full size work their 
way to the surface and pupate, forming their cocoons of their excrement 



244 



APPLIED ENTOMOLOGY 



and particles of bark, and lined with silk. These cocoons may be at the 
openings of the burrows but are more frequently fastened to the bark 
just about at the level of the ground. After 3 to 4 weeks in the pupa 
stage, the transformation to the adult is completed and the pupa breaks 

its way through the cocoon until it is 
about halfway out. Then the pupa skin 
splits and liberates the moth. 

The injury caused by this insect when 
it is abundant is often serious. The feeding 
of the borers is in the cambium layer which 
is tunneled through in an irregular way, 
interfering with the growth of the trees, 
and where these are small they are often 
girdled. The weakened trees also become 
more liable to injury and destruction by 
bark borers and other insects. 

Where the tunnels are formed, a flow of 
sap results in the pouring out of gum and 
this substance on the bark near the ground 
is usually a good indication of the presence 
of the borers. 

Control. — Of the many methods which 
have been tried, only two appear to have 
given at all valuable results. These 
are ''worming" and "mounding." Worm- 
ing is the removal of the borers late in the 
fall and again in the spring, the date for 
the spring treatment varying with the 
locality but before the borers have com- 
pleted their feeding. A day or two before 
this treatment the earth around the trunk 
should be removed to a depth of several 
inches, so that fresh gum and sawdust pro- 
duced thereafter by the borers, or below 
the level of the ground, will show. With 
these as guides where to work, the borers 
can be located and removed with a sharp 
knife, and a light, pointed wire, care being 
taken to cut as little as possible and to 
leave clean-cut edges. Then replace the earth. In the spring, following 
the "worming," mound up the earth six or eight inches high around 
the trunk and leave it there until after the moths are done flying, but 
remove it in time for the bark to harden before winter. This mounding 
forces the moth to lay its eggs further up where the bark is tough 




Fig. 240. — Larva of Peach Borer 
Moth and its work on a young 
peach tree. {From U. S. D. A. 
Farm. Bull. 908.) 



THE LEPIDOPTERA 



245 



and harder than at and below the ground level, and fewer of the borers 
are able to penetrate it to the cambium layer. 

Probably more kinds of materials have been tested for the control 
of this insect than of any other, but it is still without an entirely satis- 
factory treatment, though Paradichlorobenzine pulverized to the fineness 
of coarse salt, has given fair success recently. The ground close to the 
tree is somewhat loosened, an inch or two deep; the material is then 
evenly sprinkled around the trunk in a band an inch or two wide; then 
two or three shovels of earth are placed over it and compacted with 
the back of the shovel. Three-fourths of an ounce to an ounce of the 
material is enough for trees 6 to 15 years old. It is not entirely safe 
for use with younger trees. The base of a tree treated thus, should be 
uncovered a month or so later and left exposed for a day or two before 
recovering with the earth. 




Fig. 241. — Squash-vine Borer (Mellitia satyriniformis Hl)n.); a, male moth; b, female, 
wings folded ; c, egg.s on a piece of squash stem ; d, full-grown larva in squash stem ; e, pupa ; 
/, pupal case, found in the ground. All one-third larger than natural size. {From U. S. 
D. A. Farm. Bull. 856.) 



The Squash-vine Borer {Melittia satyriniformis Hbn.). — This pest is 
also a native of the New World, and is found from Canada southward to 
Brazil and west practically to the Rocky Mountains. It attacks the 
squash, pumpkin and occasionally the gourd, melon and cucumber, but 
does not usually, at least, infest the last two plants when the others are 
at hand. The adult moth (Fig. 241 a and b) is about the same size as, 
but a little stouter than the Peach Borer. Its fore wings are a dark, 
metalHc green, its hind wings transparent, its abdomen orange and black 
and its hind legs heavily fringed with long, black, orange and a few white 
hairs, making these legs look very large. It appears about the time the 
plants are large enough for egg-laying and feeding upon — in April or 
May in the South; in June in the Middle Atlantic States and in July in 
New England — and lays its eggs at first near the base of the plant on the 



246 APPLIED ENTOMOLOGY 

stem but later almost anywhere on it. About 200 eggs (Fig. 241c) 
are laid singly, and these hatch in from 1 to 2 weeks. The larvae 
now bore into the stem and feed, generally working toward the base of 
the plant, making holes through it to the outside here and there, through 
which some of the excrement is expelled. They become full-grown (Fig. 
24 Id) in about 4 weeks and then go a few inches into the ground to 
pupate, making dark-colored silken cocoons (Fig. 241/) mixed with dirt. 
Some soon pupate (Fig. 24 le) while others remain as larvae in their 
cocoons until the following spring. After the pupal stage has been 
completed the pupa works through the cocoon and to the surface of the 
ground and the moth then emerges from its pupal skin. 

In the South there are two generations a year of this insect: far- 
ther north there is a partial second generation, and in the northern 
part of its range there is only one, winter in any case being passed in the 
ground. 

The injury caused by these insects when they are abundant is serious. 
The burrows become wet and slimy, hastening decay and thus separating 
much of the plant from its roots. The feeding also interferes with the 
circulation of the sap to some extent. A sudden wilting of the leaves is 
generally an indication of the presence of the borers, and coarse yellowish 
excrement beneath the stems is also evidence of their activity. In some 
cases entire fields of the plants have been killed by the work of this 
pest. 

Control. — Sprays tried thus far have proved ineffective. As the 
winter is spent in the ground of the field where the insects fed, it is evi- 
dent that their food plants should not be planted 2 years in succession 
on the same land. Light harrowing of infested fields in the fall to bring 
up the cocoons and expose them to winter surface conditions, followed 
by spring plowing to a depth of at least six inches has given good results. 
Planting a few plants of very early varieties of summer squash as a trap 
crop on which the insects may lay their eggs before the real crop is 
available for them, followed by the destruction of the trap plants before 
the larvae are full-grown is helpful. Covering the stems with earth to 
induce the production of roots from the nodes along the stem will often 
enable an attacked plant to continue to grow even after its connection 
with its original roots has been destroyed. Finally, when borers are 
found in the stems they may be cut out, using a sharp knife and splitting 
the stem lengthwise where the borer is and removing it, then covering 
the stem thus treated with moist earth to aid it in healing the wound. 

Many other injurious insects belong in this family, among which the 
Imported Currant Borer boring in currant stems and killing them; the 
Blackberry Crown Borer which bores in the roots and crown of the black- 
berry and raspberry and has a 2-year life history; and the Maple Sesian 
which bores in the trunks of maples, may be mentioned. 



THE LEPIDOPTERA 



247 




Fig. 242. — Angoumois Grain Moth 
(Sitotroga cerealella Oliv.) : a, adult 
moth, about twice natural size; b, larva 
in a grain of wheat; c, pupa in another 
grain, b and c about three times 
natural size. (Modified from Sander.) 



Family Gelechiidae. — Some of the small insects which compose this 
group are leaf -miners; others feed on buds and others skeletonize leaves 
or attack plants in various ways. Many are injurious at times, the 
amount of injury done depending on their abundance which varies from 
year to year. 

The Angoumois Grain Moth (Sitotroga cerealella OViv .) . — This little 
insect, a native of Europe where it was extremely injurious in the French 
province of Angoumois, whence its name, has been known in the United 
States since about 1730 and is widely distributed but is not often im- 
portant in the more northerly states. The larva attacks wheat, barley, 
oats and corn, both in the fields and 
in storage, often destroying a large 
part of the grain. 

The adult moth (Fig. 242a) is 
small, spreading about half an inch, 
yellowish in color, slightly speckled 
with black. Winter is spent as the 
caterpillar in the grain wherever it 
may be stored, and pupation occurs in 
the spring, also in the grain, followed 
by the emergence of the adult which 
flies to the fields and lays its eggs, 
about a hundred in all, in the young 

grain heads. The eggs hatch in about a week and each tiny caterpillar 
attacks a kernel, gnawing into it (Fig. 2426) and consuming its contents. 
After about 3 weeks the larva becomes full-grown and pupates in the 
kernel (Fig. 242c) where it fed, escaping a little later as the adult moth. 
Eggs are now laid on grain ready to harvest and either in the harvested 
grain or in corn after it has been husked and is therefore accessible to 
the insects, there now follow later generations, until cold stops their 
further development which is resumed the following spring. 

Small grains and corn thus attacked are badly injured, not only by con- 
sumption of the contents of the kernels but also because of the presence 
of the bodies of the insects themselves and of their excrement which 
gives a disagreeable taste to the flour, which lacks adhesiveness and 
breaks up when stirred in water. 

Control. — When this insect is present, destroy or feed all waste grain 
and screenings and clean up all grain and refuse from places where grain 
has been stored, in early spring. Good grain should be fumigated at this 
time also, if the caterpillars are present. The purpose of this is to destroy 
the insects before they pass to the growing food plants out of doors. 
Threshing the grain soon after harvest, not keeping it in the mow long, 
is also important. Fumigation of the threshed grain for 24 hr., with 
Carbon disulfid, using 1 lb. for each 100 bu., if it is infested or heats. 



248' 



APPLIED ENTOMOLOGY' 



which is due to infestation, is an important control which should not be 
omitted. If the insect is present the sooner fumigation is given the 
sooner the loss by feeding will be stopped. 

Family Pterophoridae. — The insects of this family, though rather small, are of 
much interest, the wings being cleft for a part of the distance in from the outer 
margin toward the base (Fig. 243). In most cases the fore wing is divided into 
two such parts and the hind wing into three. A single species found in this 
country and placed in a separate family (Orneodidae, Fig. 244), has each of its 
wings divided into six parts. 





Fig. 243. Fig. 244. 

Fig. 243. — Adult Pterophorid Moth showing the cleft wings, nearly twice natural size. 
(Original.) 

Fig. 244. — Orneodid Moth showing the cleft wings. Twice natural size. (Original.) 

Most of the Pterophoridae are not of great economic importance. One species, 
however, causes some injury to the grape by webbing together the leaves, usually 
the terminal ones, and feeding within the web. As this frequently involves a 
cluster of buds which may also be fed upon, the crop may be somewhat reduced 
in this way. The only control known is to remove the webs by hand and crush 
the little caterpillars. 





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^^i_j 


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4 


i^^ 


1^ ^ ^ "" ^sk 

H/1 < 


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'''■'''^-wffipl 






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Fig. 245. — Adult Mediterranean Flour Moth (Ephestia kuhniclla Zell.), three times 
natural size. (From Herrick's Insects Injurious to the Household. By Permission of the 
Macmillan Company, Publishers.) 

Family Pyralidae. — This is a large family but most of the moths belonging here 
are small. The members of the group have very varied habits. Some fold or roll 
leaves; some bore in plant stems; some feed on stored cereals or dried fruit; one or 
two feed on wax and are pests in bee hives; others attack foliage, grass or vari- 
ous materials. Many are injurious but few can be rated as serious pests over 
the entire country. 



THE LEPIDOPTERA 



249 



The little white or brown and white moths which are so numerous in grass 
fields during the summer months, belong here. On alighting on a grass stalk 
they place their bodies parallel to the stems and fold their wings closely about 
them. Their larvte feed on grass and are sometimes quite injurious, corn and 
oats suffering severely. Early fall plowing and replowing early the following 
spring are helpful under such conditions. 

Three species are often found in houses attacking flour, meal, cereals and 
dried fruits. One species, the Mediterranean Flour Moth (Fig. 245) (Ephestia 
huhniella Zell.) spins a web which causes flour to stick in loose masses, and in mills 
and storage houses this becomes serious. The other two species are more liable 
to be found in dried seeds, fruits, etc., and often cause considerable injury. In 
storage houses and mills fumigation with Hydrocyanic acid gas is often used as a 
control, and if the place can be heated to 125° F. for about 6 hr., this also has 
proved effective. 

The Bee Moth {Galleria mellonella L.) also belongs here (Fig. 246). It is an 
enemy of the bee-keeper living in the bee hives where it feeds on wax and spoils 
the honey. Strong colonies of bees can usually protect themselves from this 





Fig. 246. Fig. 247. 

Fig. 246. — Adult Bee Moth {Galleria mellonella L.), natural size. {Original.) 
Fig. 247. — Cocoons of the Bee Moth from the inside of a hive. Natural size. 
{Original.) 



pest, particularly the Italian races. Where necessary, the bees can be transferred 
to another hive and the infested one fumigated with Carbon disulfid (Fig. 247). 

The European Com Borer {Pyrausta nubilalis Hbn.). — ^This pest of corn and 
many other plants has only recently been discovered in this country, and in 1920 
was found only in parts of New Hampshire, Massachusetts, New York, 
Pennsylvania and Ontario. It is a borer in plant stems, in which it winters as 
a partly grown larva (Fig. 248), finishing its feeding and pupating (Fig. 249) in 
its burrow in the spring. The moths appear in June and lay 300 or 400 eggs in 
small clusters on the leaves of their food plants and the larvse tunnel in the stems 
(Fig. 250), becoming fuU-grown in about 6 weeks and the moths these produce 
appear in July. Eggs for another generation are now laid and the larva? feed 
until winter, when they hibernate in their burrows. In some places, instead 
of two generations each year there is only one. 

The moths spread from about an inch to an inch and a quarter. The male is 
rather dull purplish or reddish-brown with yellow spots or a band on the fore 
wings and grayish hind wings. The female has dull yellow fore wings more or 
less marked with brown, and grajdsh-brown hind wings. The moths fly most 
freely about dusk and are only slightly attracted to lights. 



250 



APPLIED ENTOMOLOGY 



Corn, and particularly sweet corn, appears to be a favorite food of this insect, 
and where it is abundant a large part of the crop may be destroyed. Large- 
stemmed weeds such as barnyard grass, pigweed, etc., are also attacked, as well as 
dahhas, gladiolus and other cultivated plants, which complicates the problem of 
control. 

Control. — The best method for checking the ravages of this pest is the destruc- 
tion of all corn stalks to below the ground level, either by burning during the 
winter or by using as ensilage. 





Fig. 248. Fig. 249. Fig. 250. 

Fig. 248. — Part of a corn plant showing effect on the tassels of the work of the Euro- 
pean Corn Borer {Pyrausta nuhilalis Hbn.)- {From a drawing by Snodgrass, U. S. D. A. 
Bur. Ent.) 

Fig. 249. — Corn stalk split, showing the larvae of the European Corn Borer and 
their tunnels. About natural size. 

Fig. 250. — Corn stalk cut into to show the pupa of the European Corn Borer. 
Slightly enlarged. {Both figures ft om drawings by Snodgrass, U. S. D. A. Bur. Ent.) 

Family Limacodidae (Slug Caterpillars) . — The insects belonging to this family 
are of Uttle importance from an economic standpoint, but their larvse are curious 
in appearance, having little resemblance to ordinary caterpillars. Instead, they 
are slug-like, short and rather stout, quite flat beneath, and appear to slide 
along rather than crawl. Many have spines and rather showy, colored markings, 
in some cases with soft, fleshy projections sometimes partly or entirely covered 
with hairs. The Oriental Moth {Cnidocanipa flavescens Walk.) several times 
imported into this country from Asia by accident, has estabhshed itself in Eastern 
Massachusetts but is not apparently of much importance, though the spines on 
the caterpillar cause a nettling of the skin of a person where the insect has been 
touched. 

Family Psychidae (Bag Worms) . — The caterpillars of a few species of moths 
in this country construct silken bags around their bodies, partly covered with 



THE LEPIDOPTERA 



251 




Fig. 251. — Common Bag Worm {Thyridopteryx ephemerceformis Haw.): 10, bag, as 
seen in winter; 11. same, cilt open, showing pupa case and eggs; 12, eggs; 13, young larva; 
14, cases of young larvae on a twig; 15, older larvae in tbeir bags, one hanging by a thread 
it has spun; 16, full-grown larva removed from its case; 17, full-grown larva, crawling; 
19, adult (wingless) female Moth; 20, adult male Moth; 22, bag of male with empty pupa 
case protruding from its lower end. All natural size except 12 and 13 which are greatly 
enlarged. {From Houser, Ohio Agr. Exp. Sta. Bull. 332: After Felt.) 



252 



APPLIED ENTOMOLOGY 



twigs or other parts of the plant on which they feed. The female is wingless and 
lays its eggs within the pupa case or skin she vacated on becoming adult. Only 
one species, the Common Bag-worm {Thyridopteryx ephemerceformis Haw.) is of 

much importance, but where this is plentiful 
the plants on which it feeds may suffer con- 
siderably (Fig. 251). It occurs from Massa- 
chusetts west to Nebraska and south to North 
Carolina, Tennessee and Texas. Spraying in- 
fested trees as soon as the eggs hatch in the 
spring, with arsenate of lead, standard formula, 
is usually a sufficient control without a second 
application later. 

Family Geometridae (Inch worms. 
Span worms or Measuring worms). — This 
is a large family in this country and the 
moths vary greatly in size, some being 
very small while others may spread nearly 
two and one-half inches. They nearly all 
have rather delicate wings and are fragile 
creatures. 

The larvae (Fig. 252) have a peculiar 
appearance when moving, as the feet which 
are usually present near the middle of the 
body in most caterpillars, are lacking in 
this group, leaving only the three regular 
pairs near the front end and two pairs at 
the hinder end. In consequence, walking 
is accomplished by bringing the hinder 
end up as closely as possible to the front 
end, the body forming at this time a loop. 
Then the front legs let go their hold and 
the body is straightened out to find a 
place where the front legs can grasp and 
hold on. This striking method of locomo- 
tion has led to the common names given 
to the caterpillars in this family. 

Another feature of interest about these 
larvae is that many of them are colored and 
formed so as to resemble twigs. When 
disturbed the caterpillar releases the grasp 
of its front feet and straightens out, standing at an oblique angle to the 
twig it is holding on to, and resembles a dead twig of the plant. Some 
have markings which make them resemble twigs having buds, leaf-scars 
or scales of the bark, thus increasing their deceptive similarity. 




Fig. 252. — Two "Inch Worm" 
larvae, the lower one crawling, the 
upper one hanging outward like a 
twig. Compare with real twig just 
above, on opposite side. (From 
Linville and Kelly, General Zoology.) 



THE LEPIDOPTERA 



253 



The food plants of the insects in this family are very numerous. 
Trees and shrubs of many kinds including fruit trees, currant and goose- 
berry bushes, cranberries and other plants of value to man, suffer from 
the attacks of these insects, though few are regularly injured, the pests 
in most cases being destructive only for a year or two, then disappearing, 
at least for the most part, during quite a period. 

Canker Worms. — There are two species of Geometers which are 
widely distributed over this country and which at times do serious damage 
to fruit and shade trees. They are known as Canker Worms, and while 
they differ in certain features, have much in common. In both species 
the pupal stage is passed in the ground: in both, the female is wingless: 
in both, the eggs are laid on the twigs of the trees, and in both the cater- 
pillars feed at about the same time in the spring. 

The Fall Canker Worm (Alsophila pometaria Harr.) occurs in nearly 
all parts of the Northern United States as far west as Wisconsin, and 
south at least through the Middle Atlantic States. It has also been re- 





FiG. 253. Fig. 254. 

Fig. 253. — Male Fall Canker Worm {Alsophila pometaria Harr. ), about natural size. 
{From Britton, Eighth Kept. Ent. Conn. Agr. Exp. Sia. 1908.) 

Fig. 254. — Adult Female Fall Canker Worm on a cluster of eggs. About 2^^ times 
natural size. {From Houscr, Ohio Agr. Exp. Sta. Bull. 332.) 



ported from Colorado and California. The adult male moth (Fig. 253) 
spreads about an inch and a quarter, its wings light gray with faint 
markings. The female (Fig. 254) is light gray, and wingless. The 
moths usually appear late in the fall, escaping from their pupae in the 
ground, and the females crawl up the tree trunks to the twigs where they 
lay their eggs (Fig. 254) in clusters. These eggs hatch the following 
spring, as the leaves develop, and the caterpillars (Fig. 255) feed on the 
foliage until full-grown some time in June in the Northern States, and 
earlier farther south. During this time they often drop from the leaves 



254 



APPLIED ENTOMOLOGY 



some distance, spinning a thread as they go, and up which they return 
to resume their feeding. A sudden jar of an infested tree will cause 
great numbers to drop or "spin down" several feet in this way. When 
feeding has been completed the larvse enter the ground and pupate a 
few inches below the surface in a silken cocoon, from which the moths 
escape late in the fall. 




Fig. 255. — Fall Canker Worm caterpillars feeding on Elm. Natural size. 
Eighth Rept. Ent. Co7in. Agr. Exp. Sta. 1908.) 



(From Britton, 



The Spring Canker Worm {Paleacrita vernata Peck). — The adult 
male of this species averages slightly less in its wing-spread than the 
Fall Canker Worm and its wings are somewhat lighter in color. It 
occurs throughout the Eastern United States except in the South and has 
also been taken in Texas and California. It is particularly injurious 
at times in the Mississippi Valley. This pest escapes from its pupa in 
the ground, as the adult, very early in the spring, and the females crawl 
up the trees on which they lay their clusters of eggs, frequently under 



THE LEPIDOPTERA 



255 



loose bark or in crevices. These eggs hatch about the time the leaves 
open and the larvae feed during about the same period as the other species, 
and enter the ground to pupate at nearly the same time. This insect 
also has the habit of spinning down on a thread when disturbed. 

Control of Canker Worms. — The wingless condition of the females 
which necessitates their crawling up the trunks of the trees in order 
to reach the places where their eggs are laid, offers an opportunity 
for control by banding the trunks, in the fall for the Fall Canker Worm, 
and at the first warm days after winter has broken (even in February 
in New England, in some seasons) for the spring species, either with 
sticky bands which the insects are unable to cross, or with loose fluffy 
cotton in which they become entangled. Care should be taken to keep 
the bands fresh or in order so that no gaps through which they can crawl, 
or bridges of their dead bodies over which they can cross, are formed. 
If the caterpillars are already feeding when their presence is discovered, 
spray with arsenate of lead, standard formula. 




Fig. 256. — Silk Worm {Bumbyx uiori L.) : adult moth and its cocoon. 

{Original.) 



About natural size. 



Family Bombycidae (True Silk Worms). — The only representative of 
this family in North America is the Silk Worm {Bombyx mori L.) intro- 
duced many years ago because of the silk obtained from its cocoon. 
It does not appear to have established itself anywhere in this country 
and silk-raising has not proved profitable here because of the cost of 
the labor required, as compared with that in the Orient. 

The adult moth (Fig. 256) spreads about an inch and three-quarters 
and is creamy-white in color, with two or three faint lines across the fore 
wings. The larvse feed on the leaves of the mulberry and Osage orange 
trees, and when full-grown leave their food and spin their cocoons (Fig. 
256). When spinning has been completed these are gathered and the 
insects within are killed by heat or fumigation. Now the loose silk of the 
outside is removed and the cocoons are ready to market. Nearly 
73,000,000 lb. of raw silk were produced in the world in 1918, and the 
importance of the industry is enormous. 



256 



APPLIED ENTOMOLOGY 



Family Lasiocampidae (The Lasiocampids). — This small family 
includes several species which are common and at times quite important 
pests. The moths are of only medium size, with rather stout bodies, 
antennae fringed on one side (pectinate) and with a large shoulder at 
the base of the hind wing, instead of a frenulum. The larvae feed on 
the leaves of trees. 

The Apple-tree Tent-caterpillar {Malacosoma americana Fab.). — 
This native insect is at times a pest for several years in succession, after 
which it practically disappears for some time. It is found almost every- 
where from Canada to Florida and west to the Rocky Mountains. From 

there to the Sierra Nevada Moun- 
tains another species having 
similar habits occurs, while on 
the Pacific Slope several others 
are present. 

The adult moth (Fig. 257) is 
rather stout, with a reddish- 
brown body and wings, the front 





Fig. 257. Fig. 258. 

Fig. 257. — Adult Apple-tree Tent-caterpillar {Malacosoma americana Fab.), about 
natural size. {From Sanderson, Insects Injurious to Farm, Garden and Orchard; after Lowe.) 

Fig. 258. — Egg belt of the Apple-tree Tent-caterpillar, encircling a twig. Natural 
size. {From Britton, Thirteenth Rept. Ent. Conn. Ag-^. Exp. Sta. 1913.) 



pair of which have two whitish lines crossing them. The male spreads 
about an inch and a quarter and the female about half an inch more. 
They fly at night and do not feed as adults. The wild cherry and apple 
appear to be the preferred food plants of the caterpillar, but other fruit 
and shade-trees are sometimes fed upon. 

The moths appear during the early part of the summer and lay their 
eggs (Fig. 258), 200 or 300 in number, in belts around small twigs, one 
belt probably being all that is laid by one insect. These belts more 
or less completely surround the twig, and after depositing a belt, the 
insect covers the eggs with a layer of a brown, sticky substance, beveled 



THE LEPIDOPTERA 257 

down to the twig at each end, which soon hardens and ghstens. Within 
the eggs the larvae develop and are ready to hatch by winter, but remain 
within the egg-shells until spring. They then leave the eggs and may 
feed first on the material covering the eggs, but soon crawl together to 
some near-by fork of the tree and there spin a web (Fig. 259) in which 
to live. From this they go out during the day to feed, spinning a thread 




Fig. 259. — Tent of the Apple-tree Tent-caterpillar, about half natural size. {Original.) 



as they go, perhaps to aid them in finding their way back. As they grow 
the tent or web is enlarged by the addition of outer layers and may be 
nearly a foot long and seven or eight inches across before the larvse are 
full-grown, the feeding period being about 6 weeks. 

Though at first very small, the larvae grow rapidly and when of full size 
are about two inches long, black with a white stripe along the middle of 
the back and a row of pale-blue spots on each side, with a velvety-black 
spot in front of each blue one (Fig. 260). Fine yellowish hairs are also 
present. 

When about through feeding the caterpillars scatter and finally 
spin rather large, quite thick, white cocoons in any protected places 

17 



258 



APPLIED ENTOMOLOGY 



they may find, and within these they pupate, taking about 3 weeks 
in this stage before the moth appears. 

An unusual feature in this hfe history is the long period spent in the 
egg, which may be almost 10 months. 

Control. — Although this insect has numerous enemies both among 
birds and insects, there are periods during which these are unable to 
prevent trees being stripped by the pest. In general, the calyx spray 
used on apples and pears for the Codling Moth is sufficient to destroy 




Fig. 260. — Larvae of the Apple-tree Tent-caterpillar, natural size. (From Britton, 
Thirteenth Rept. Ent. Conn. Agr. Exp. Sta. 1913.) 

this caterpillar also. On wild cherry and other trees not usually sprayed, 
however, it finds a breeding place from which the fruit trees may be 
restocked, and such trees should also be cared for, to prevent this. 
Examination of such trees any time between August and March, to find, 
cut off, and burn the eggs, and the destruction of the caterpillars while 
in their tents on rainy days or at night, either by crushing or by burning 
with a torch, are desirable auxiliary treatments in addition to spraying. 
The torch method should not be used on young fruit trees, however, as 
holding the torch at a fork a moment too long is liable to injure this 



THE LEPIDOPTERA 



259 



place, and in later years the injury will show as the fork becomes an 
important one, in the form of a splitting at that point under the weight of 
the branches and fruit beyond. 

The Forest Tent-caterpillar {Malacosoma disstria Hbn.) is also a 
native of North America. It greatly resembles the last species, both 
in appearance and in some of its habits, but though occasionally found 
feeding on some of the same food-plants, it appears to prefer the oak, 
maple and other forest and shade-trees. 

The adult (Fig. 261) is of about the same size and general appearance 
as the Apple-tree Tent-caterpillar, but the general color is lighter brown 
and the lines or bands across the fore wings are darker, instead of lighter 




Fig. 261. Fig. 262. Fig. 263. 

Fig. 261. — Adult Forest Tent-caterpillar {Malacosoma disstria Hbn.), natural size. 

{Original.) 

Fig. 262.^Egg belt of Forest Tent-caterpillar, natural size. {Original.) 

Fig. 263. — Full-grown larva of the Forest Tent^caterpillar. About two-thirds natural 

size. {Original.) 



than the ground color. The egg belts (Fig. 262) are similar but quite 
squarely cut off at their ends instead of being rounded down to the twig: 
the caterpillar (Fig. 263) has a row of rather oval white spots instead of 
a white stripe along its back, and its sides are noticeably light blue, 
with two broken, longitudinal, yellow lines. The caterpillars make 
no tents but scatter after hatching. Otherwise the life history, time 
spent in the different stages and the periods of the year during which 
these occur are the same in both species. 

Control. — Where the caterpillars can be reached by spra^^s, control is 
comparatively simple as with the Apple-tree Tent-caterpillar. In 
forests, however, where large trees are stripped of their foliage, this 
method is rarely practicable. Destruction of the egg-belts is of value, 
but these can seldom be reached in any numbers, being usually high up 
on the small twigs. Jarring the trees where these are small enough for 
this, will cause many of the caterpillars to drop to the ground, and by the 
use of stick}' or cotton bands they may be prevented from crawling 
back again. The caterpillars frequently cluster in large numbers on the 
trunks of the trees and at such times, spraying these clusters with any 



260 APPLIED ENTOMOLOGY 

strong contact insecticide is an effective treatment. For the most part, 
however, little can be done and in "sugar bushes" extensive defoliation 
with a consequent reduction of the vitality of the tree and of the sap 
flow will follow, only relieved after a year or two by an increase in 
the enemies of this insect to such an abundance as to reduce it to 
unimportance. 

Some of the western species of Tent-caterpillars make tents, while 
others do not. Occasionally one species or another may become so 
abundant as to strip everything in one place, and in such cases the larvae 
crawl off in enormous numbers seeking for more food. In one instance 
their line of march was across a railroad, where they were crushed by the 
car wheels until the rails became so slippery that trains were unable to 
run except by sweeping the caterpillars off or by blowing them off the 
track ahead of the engine by jets of steam! 

Family Lymantriidae (The Tussock Moths). — This family, though 
small in numbers in this country, includes some serious pests. The 
moths are of medium size, and the females in some cases are either 
wingless or nearly so. The legs are rather thickly clothed with hairs. 
The group as a whole is one of night-flying insects but a few fly freely 
in the day time. 

The larvse are often highly, even brilliantly colored, and are thickly 
covered with hairs. These may be quite uniformly distributed, but in 
some cases there are also bunches or "tussocks" of them projecting some 
distance from the skin, and long, slender "pencils," composed of a few 
hairs which may be a quarter as long as the body of the caterpillar. 
Most of them feed on the foliage of trees but some have a wide range 
of food plants. 

The White -marked Tussock Moth {Hemerocam'pa leucostigma 
A. & S.). — This common species is found along the entire Atlantic Coast 

from Nova Scotia to Florida and westward at 
least to Nebraska, and has also been reported 
from Oregon. It is mainly a pest of shade- 
trees, and most injurious in and near cities 
and towns, but at times attacks fruit-trees and 

Fi«. 264.-Adult male of ^^uses much injury, 
the White-marked Tussock The adult male moth (Fig. 264) Spreads about 

Moth {Hemerocampa ^^ j^^j^ ^^^ -^^ wings are grav with wavy dark 

leucoshgma A. and b.), ' ° r> ^ ^ ^ 

about natural size. (From bands and light marks. Its antennae are heavily 
ColnX^'^st. ito?.) ^"' ^^i^ged. The female (Fig. 265) is wingless, 
with a gray body. 
The winter is spent in the egg stage, the larvse hatching in the spring, 
feeding until full-grown, on foliage, then crawling away to pupate, some- 
times on the twigs but usually either on the bark of the trunk or lower 
limbs, or on other objects near-by. The cocoons are composed of silk 




THE LEPIDOPTERA 



261 



mixed with hairs from the body of the caterpillar and are gray in color. 
The female on emerging from the pupa stage crawls to the surface of 
the cocoon and later lays there from 300 to 500 eggs (Fig. 265) which she 
then covers with a white froth which soon hardens and forms a crust 
{♦overing and hiding the eggs. This white crust on the gray background 
of the cocoon and the generally dark bark of the tree makes the eggs very 
conspicuous objects. 

The eggs soon hatch and the caterpillars thus produced feed on the 
leaves until full-grown (Fig. 266) then pupate as in the preceding genera- 
tion and the moths appearing later, also lay their eggs on their cocoons 
and cover them with white froth. It is probable that throughout the 





Fig. 265. Fig. 266. 

Fig. 265. — Adult female of the White-marked Tussock Moth with an egg mass covered 
by a white crust, resting on her cocoon. About natural size. (Modified from N. Y. Agr. 
Exp. Sta. Bull. 312.) 

Fig. 266. — Caterpillar of White-marked Tussock Moth. Note the four "tussocks" of 
hairs. Slightly reduced. (Modified from N. Y. Agr. Exp. Sta. Bull. 312.) 

northern part of the territory inhabited by this insect, these eggs will be 
laid so late in the season that they will not hatch until the following 
spring and the white crusts covering them will therefore be prominent 
objects during the winter. We accordingly find two generations of this 
insect in the Middle States; one in the North, and there are probably 
three in the South, corresponding to some extent at least, with the 
length of time during which food is available. 

The moths are seldom seen, though the males fly somewhat during 
the day. The egg clusters, however, are objects which attract attention 
and the caterpillars are highly colored and so peculiar in appearance as 
to be very noticeable. A full-grown caterpillar is nearly an inch and a 
half long, with a bright red head and also two red humps above, near the 
hinder end. Between the head and the middle of the body is a row of 
four large cream-colored tufts or "tussocks" of hairs standing up some 
distance above the surface of the body. The side is grayish with a yellow 
band above and below. Projecting upward, forward and outward from 
just behind the head are two slender clusters of black hairs or "pencils" 



262 APPLIED ENTOMOLOGY 

about half an inch long, and a single similar but gray pencil of hairs 
projects upward and backward from near the hinder end of the body. 
These characters make the caterpillar of this insect a very striking and 
noticeable animal. 

Control. — Gathering and destroying the egg clusters or applying 
creosote to them freely enough to penetrate the crust and reach all the 
eggs beneath are methods which can be made use of whenever the clusters 
are observed. Spraying for the caterpillars, using arsenate of lead, 
standard formula, is also effective. Trees not infested, whose branches 
do not touch those of other and infested trees, can be protected by the 
use of sticky or cotton batting bands around their trunks during the 
periods when the caterpillars are crawling. 

The Antique or Rusty Tussock Moth {Notolo-phus antiqua L.). — This 
is a European insect but widely distributed in North America. The 
male moth averages about as large as the White-marked Tussock Moth 
and has rusty-brown wings, each fore wing with a small white spot. 
The female is wingless. The eggs are laid on the cocoon of the parent 
moth but without any white crust to conceal them, and the caterpillar 
has a black head. Of the four tussocks on the back, the first two are 
black at first but become whitish later, like the others. The pencils 
of hairs just behind the head and at the end of the abdomen resemble 
those of the other species and an additional pair is also present, one on 
each side of the body a short distance behind the head. 

The life history of this insect is probably similar to that of the last 
species, though the number of generations in different parts of the country 
does not appear to have been worked out. In the Northern States there 
is one each year. Control measures are the same for both species. 

The Gypsy Moth {Porthetria dispar L.).— This European insect was intro- 
duced into this country near Boston, Mass., by accident, about 1869 and has 
gradually spread until it now covers the greater part of the New England 
States. It has also appeared in other localities but these places were dis- 
covered early and the insects exterminated. 

The adult male moth (Fig. 267) is brown with some yellowish markings, and 
spreads about an inch and a half. It flies freely during the day. The female 
has nearly white wings, with dark markings; a stout, heavy body covered behind 
with buff hairs: its wings spread about two inches, and though having well-de- 
veloped wings, this sex does not fly. 

Winter is passed in the egg stage, the caterpillars hatching in the spring and 
feeding on many kinds of leaves, though the apple, oak, willow, alder and birch 
appear to be favorites, and shrubs and herbaceous plants do not escape. Ash 
is not fed upon, nor is pine during the first two instars. 

Feeding until early in July the caterpillars become full-grown (Fig. 268) and 
may then be nearly three inches long and as large as a lead pencil. They are 
brown, partially hairy, the hairs being somewhat clustered, and on the back bear 
five pairs of blue spots, followed behind by six pairs of red ones. At the end of 



THE LEPIDOPTERA 



263 



the feeding period the caterpillar crawls to any satisfactory place, usually the 
underside of some limb or on the trunk, and there spins a few threads to hold its 




Fig. 267. — Adults of the Gypsy Moth {Porthetria dispar L.) ; female on left; male on right. 
Natural size. (Fro7n Britton, Fifth Rept. Ent. Conn. Agr. Exp. Sta. 1905.) 

body in place rather than for concealment or protection, and in this exceedingly 
scanty cocoon it pupates (Fig. 268) and after a period of from a week to 17 or 
18 days, the moth emerges. 




Fig. 268. — Pupae and larva? of the Gypsy Moth, natural size. 
Ent. Conn. Agr. Exp. Sta. 1905.) 



{From Britton, Fifth Rept. 



The eggs are now laid in oval clusters throughly covered by buff hairs from 
the abdomen of the moth, and each cluster may contain from four to five hundred. 
There seems to be Uttle choice where the clusters are placed, many being on the 



264 APPLIED ENTOMOLOGY 

trunks and limbs of the trees, but others are found in cavities in the trunks, on 
the stones of stone walls, even in the middle of the wall, in tin cans, and in fact, 
anywhere the female may crawl to. They hatch the following spring. 

Distribution appears to be accomplished by the crawling of the caterpillars; 
by carrying to other places objects on which egg-clusters have been deposited; 
by caterpillars spinning down on threads from the trees onto passing vehicles; 
and by the wind. 

The injury caused by this insect is often very serious. The caterpillars 
have voracious appetites and eat large amounts and their abundance has often 
resulted in the stripping of large areas, which repeated several years in succession 
usually causes the death of the trees. With evergreens, a single defohation is 
usually sufficient to kill the trees, and in many parts of Eastern Massachusetts 
the thinning of woodland areas in consequence of the work of these insects, is 
very evident. 

Parasites and other enemies of the Gypsy Moth have been introduced in 
large numbers by the Federal Government, and where these have become abun- 
dant they have done good work, though of course nothing like extermination of 
the pest has been accomplished. A wilt disease present in favorable seasons, 
kills many of the larvae at such times. In general though, outbreaks of this 
insect in any locality are not repressed by their natural enemies for several years, 
and in the meantime the damage is great. This condition therefore calls for 
the use of control methods. 

Control. — The egg clusters constitute one place where control measures can 
be applied. It is much easier to kill 400 or 500 insects concentrated in a space 
an inch square or less, than the same number in the larval stage, scattered over 
a tree. Soaking the egg clusters at any time after they are laid until they hatch 
the following spring, with creosote to which a little lampblack has been added 
(to show by its color which clusters have been treated and which have not) is a 
good treatment. Care must be taken, however, in using this material, to take 
enough to reach all the eggs in the cluster. Usually a swab on the end of a 
stick, soaked in the creosote, is used for this work. The difficulty with this 
method is that of finding all the egg clusters in their varied places of concealment. 

While the caterpillars are very small, spraying infested trees and other 
plants with arsenate of lead, using about 5 lb. of the paste (2>^ lb. of the powder) 
in 50 gal. of water, is a good treatment, but as the larvse become larger they 
seem to develop a greater resistance to poisons and spraying becomes less 
effective. 

As the larvse feed largely at night and seek concealment during the day, put 
loose bands of burlap around the trunks of infested trees, where they may hide 
in the daytime. Success with this method of control is dependent upon daily 
visits to the bands and the destruction of the caterpillars found under them. 

Sticky bands around the trunks of non-infested trees will keep the caterpillars 
off such trees as long as the bands remain fresh and in good order. 

As the caterpillars do not feed on the pine until after they have passed their 
second instar, pure stands of pine may be protected by removing all under- 
growth other than pine and banding the trees as above, to prevent older larvae 
from crawling to them from places outside where they have obtained their earlier 
food. 



THE LEPIDOPTERA 



265 



The Brown-tail Moth (Euprodis chrysorrhoea L., Fig. 269). — This is another 
European pest which was accidentally introduced into this country near Boston, 




Fig. 269. — Brown-tail Moth {Ewprociis chrysorrhoea L.): 2, adult mule; 3, adult female 
moth; 4, egg cluster on leaf, covered with hairs from body of parent; 5, caterpillars feeding. 
About natural size. {From U. S. D. A. Bur. Ent. Bull. S7.) 

reaching there about 1892. Since that time it has spread as far as Nova Scotia 
and New Brunswick, and also practically covers all of New England. 

The moths are white except for the abdomen which has a few brown hairs, 
and the tip is covered by a tuft, large in the female, of golden brown hairs— 



266 APPLIED ENTOMOLOGY 

the character which has given this insect its common name. The moths spread 
about an inch and both sexes are strong fliers, appearing early in July. They 
are somewhat attracted to lights but in most cases the females found thus 
attracted, appear to have already laid their eggs. The moths lay 200 or 300 
eggs in a cluster, usually on the leaves, and cover them with brown hairs from 
the tip of the abdomen. They hatch in from 2 to 3 weeks and the little cater- 
pillars feed on the foliage in company during the early fall, leaving the veins, and 
thus skeletonizing the leaves. Early in September they go together to the tip 
of some twig and there spin a very tough, dense, silvery tent incorporating 
some of the leaves in it, to use as their resting place for the winter. The size and 
form of this tent will vary with the number of caterpillars contributing to its 
formation, but it is usually three or four inches long and an inch or two in 
diameter at its widest p lace. After the leaves fall these tents at the tips of 
the twigs are very conspicuous objects during the winter. At the time of the 
formation of the tent the caterpillars are about one-third of an inch long. 

In the spring as soon as the leaf-buds begin to open, the caterpillars leave 
their tents and scatter, feeding until June when they become fully grown and 
are about an inch and a half long, brown, slightly mixed with orange, fairly well 
covered with fine reddish-brown hairs, and with two bright red tubercles, one 
behind the other, on the middle line of the body above, near the hinder end. 
These red tubercles are very distinctive and give a positive recognition of this 
caterpillar. 

The hairs just mentioned are delicate, brittle, barbed in some cases, and 
secrete a poisonous fluid very irritating to the skin. As the caterpillars molt 
these hairs are liable to be broken off and carried through the air to persons or 
onto their clothing, and a painful rash somewhat resembling that caused by 
poison ivy is produced, known as the "brown-tail rash." 

Pupation usually occurs among the leaves and after about 20 days is followed 
by the emergence of the adult moths. The cocoon, though more developed than 
with the Gypsy Moth, is not very thick or dense, and the pupa can generally be 
seen through its walls. 

Control. — -Cutting off and burning the winter tents at any time between Sep- 
tember and April is an effective method of control where the size of the tree is 
such that the tents can easily be reached. Spraying with arsenate of lead, 
standard formula, either in the fall if no fruit is involved, or when the larvae 
first resume feeding in the spring, is also a good treatment. 

Many of the parasites imported by the Federal Government to destroy 
the Gypsy Moth, attack this species also and appear to have done good work. 
For the last few years this insect has been rather less abundant than was pre- 
viously the case. Whether this condition will continue, or outbreaks will recur 
from time to time cannot now be determined, but probably the latter will be 
true. 

Family Notodontidse (The Prominents). — The Prominents as the insects 
of this family are often called, are of medium size as adults and usually not at all 
brilliantly colored. Few of them are serious pests, and then generally only for 
a year or two at a time. The caterpillars of the different species differ greatly 
in appearance, some having dorsal humps or projections, others a much elongated 
end of the body, or other modification of the typical form of caterpillar. 



THE LEPIDOPTERA 



267 



One part of this family consists of moths known as the Datanas. The larvae 
of these insects feed on orchard, shade and forest trees, keeping together in 
groups, and when resting or disturbed they bend the ends of the body nearly at 
right angles to the middle part, in a very characteristic attitude. They feed 
during July and August and when full-grown are about two inches long. One 
species is common on the apple (Figs. 270, 271) : others occur on the oak, walnut, 
hickory and other plants. The presence of 100 or 200 caterpillars feeding to- 
gether on a single branch, and of 
considerable size as they get older, 
often disturbs the owners of infested 
trees who unnecessarily fear serious 
injury to their trees. 

The fact that the caterpillars feed 
in groups renders control easy, how- 
ever, either by removing the groups by 
hand or by spraying the region at- 
tacked, with a stomach poison, which 
is very effective for these insects. 

Another Notodontid having similar 
habits and found at the same season 
is the Red-humped Apple-tree Cater- 
pillar (Schizura concinna S. & A., 
Fig. 272). The larva (Fig. 273) has a 
red head ; a red hump a short distance 
behind; a double row of black spines 





P'iG. 27U. Fig. 271. 

Fig. 270. — Adult Moth of Yellow-necked Apple-tree Caterpillar {Datana mmiatra 
Dru.), slightly less than natural size. {Oii'jinal.) 

Fig. 271. — Yellow-necked Apple-tiee Caterpillars on a branch, showing characteristic 
attitudes assumed when disturbed. Natural size. (From Britton, Eighteenth Rcpt. Ent. 
Conn. Agr. Exp. Sta. 1918.) 

along its back; and its body is narrowly striped with yellow, black and white. 
Control is the same as for the Datanas. 

Family Dioptidae. — ^This family appears to have but one North American 
representative, found only on the Pacific Slope. It is known as the California 
Oak Worm {Phryganidia calif ornica Pack.), and the caterpillar feeds upon the 
leaves of the hve oak and deciduous oaks. The. adult moth (Fig. 274) is light 
brown with darker veins and a wing-spread of about an inch and a quarter. 
The eggs are laid on the leaves of the oaks and various other plants in October 



268 



APPLIED ENTOMOLOGY 



and November, and hatch during the 5 months following. Those on the decidu- 
ous oaks fall with the leaves, and larvae from them rarely find anything to feed 
upon and therefore die. The eggs laid on the live oak, eucalyptus and chestnut, 
however, produce caterpillars (Fig. 275) which can generally obtain food and 
they become full-grown in May and 
June and pupate in any protected 
place, spinning no cocoon. The 
moths from these pupae emerge after 
about 2 or 3 weeks and lay their eggs 
for a second generation, the larvae of 
which feed during the last of July, 
August and September. Pupation fol- 
lows, after which the moths appear 
and lay their eggs as already indicated. 





Fig. 272. 



Fig. 273. 



Fig. 272. — Adult Moth of Red-humped Apple-tree Caterpillar {Sdtizura concinna S. 
and A.), natural size. {Orighial.) 

Fig. 273. — Red- humped Apple-tree Caterpillar in feeding position. Somewhat en- 
larged. {From Britton, First Ript. Ext. Conn. Agr. Exp. Sta. 1901.) 

When abundant, the trees upon which these insects feed are liable to be 
entirely stripped of their foliage and this sometimes happens over large areas. 

Control. — Spraying the trees when the caterpillars are abundant, as they 
begin to feed, with Arsenate of lead, 4 or 5 lb. of the paste (2 or 2>2 lb. of the 





Fig. 274. Fig. 275. 

Fig. 274. — California Oak Worm Moth {Phryganidia californica Pack.), about natural 
size. {After Essig, Inj. and Benef. Ins. of Cat.) 

Fig. 275. — Caterpillar of the California Oak Worm, natural size. {Modified from 
Essig, Inj. aiid Benef. Ins. of Cat.) 

powder) in 50 gal. of water is effective where the size of the trees permits this 
treatment. Power sprayers and nozzles giving a fine mist are the most effective 
for this purpose. 

Family Noctuidae (The Owlet Moths). — The Noctuids form the largest 
family of moths in this country and are everywhere abundant. Within 



THE LEPIDOPTERA 



269 



the group there are great differences in the appearance of the moths 
and in the habits of their larvae. Lochhead has divided the family into 
nine sections, based mainly on differences of larval habits. 

Some members of the Noctuidse are known as the Catocalas or "Under- 
wings." Some of these are quite large, spreading three inches or more, the fore 
wings with quiet colors and marked so that they resemble the bark of trees (Fig. 
276) . One has fore wings similar to the bark of the white birch : another resembles 
the bark of the beech, and many kinds of trees are thus imitated in color and 
markings. The hind wings are brightly, often brilliantly colored and it appears 
to be the habit of the moths, which fly at night, to rest during the day on the tree 
trunks whose bark their fore wings resemble, folding these over their gaudy hind 
wings, in this way obtaining through concealment, protection from their enemies. 
How far in the course of thousands of generations, the weeding out by these 
enemies of those least closely resembling the bark, leaving behind to continue 




Fig. 276. — Catocala Moth, natural size. {.Original.) 



the race the closest imitators of the bark, has resulted in giving to the present 
members of the group a closer resemblance than their ancestors, is a question for 
speculation. The larvsp of the Catocalas feed on foUage but are rarely if ever 
injurious enough to be of importance. 

The largest Noctuid found in this country is known as the Black Witch 
{Erebus odorata L.). It does not live in the United States, being an inhabitant 
of the tropics, but its size and powerful wings which often spread six inches, 
enable it to fly long distances and it is often captured in the late summer and 
fall in the Northern United States. It has dark wings of various shades of 
brown, and a small "eye" spot in each fore wing. 

The Cotton Worm {Alabama argillacea Hbn.). — The Cotton Worm is not a 
native of this country but of more tropical countries, from which it frequently 
comes and attacks cotton in the Southern States. The moths (Fig. 277) are of a 
nearly uniform reddish-brown or tawny color, and spread a little over an inch. 
They lay their eggs singly on the cotton leaves and these eggs hatch in from 3 
to more than 20 days, according to the temperature. The caterpillars are at 
first yellowish-green with pale yellow heads. Later they vary much in color and 
markings, some changing little, while others acquire a black stripe along the 
middle of the back, with a fine central yellow line, and each segment has four 




270 APPLIED ENTOMOLOGY 

black dots above. The full-grown larva webs a leaf or two together and pupates 
in this place, remaining there a varying length of time before the adult emerges. 
Fall flights northward of Cotton worm moths occur frequently and may 
extend into the Northern States and Canada, where these insects are sometimes 
found abundantly in September and October. 

Control. — Dry arsenate of lead dusted over the plants when these insects 
first appear, using from 2 to 4 lb. per acre, according to the size of the plants, 

appears to be a satisfactory treatment. 
It is usually applied while the dew is on 
the plants. 

The Dagger Moths are leaf feeders on 
various shrubs and trees in their larval 
stages. The fore wings of the moths are 
various shades of gray in most cases, and 
the larvae are usually quite well covered by 
rather uniformly distributed gray hairs. 
Several species are known as Green Fruit 

■^'°- ,?7^'~'^1V'^ ™°*^ °L ^'^® worms, the caterpillars being greenish, with- 
Cotton Worm (Alabama argillacea ' . , \. i- 7 i i 

Hbn.), about natural size. (Original.) out hairs, and feedmg on the leaves and 

small fruit of apple and other trees during 
the later spring months. They are not often seriously abundant. 

Some of the Noctuids are Stalk Borers, tunneling in the stems of cultivated 
and other plants, among the plants affected in this way being corn, tomatoes, 
potatoes, asters, dahlias, etc. The larva feeds during the summer months and 
as a rule pupates in the lower part of its tunnel. Accordingly, all wilted plants 
should be examined, and if a borer is present the plant should be destroyed 
with the borer either as larva or pupa, within it. 

The Corn Ear Worm {Chloridea ohsoleta Fab.). — This widely distrib- 
uted pest is known by several common names, such as the Cotton boll- 
worm, tomato fruitworm and false budworm of tobacco, in addition to 
the one first given. In the South it attacks cotton bolls and tobacco seed 
pods, as well as tomatoes and corn which are its usual food in the North. 
It is present practically everywhere in the world between the parallels of 
50° north and south latitude, and its original home is problematical. 

The adult insect (Fig. 278a) spreads about an inch and three-quarters 
and is extremely variable in color, so that several varieties have been 
recognized. It ranges from a pale reddish-brown to olive, with a greenish 
tinge toward the outer margin of the fore wings, with darker bands and 
spots, and the hind wings are lighter, with dark veins and a blackish 
shade crossing from one outer angle to the other, leaving more or less of a 
lighter color between this and the outer margin. 

The insect appears to pass the winter as a pupa in the ground, the 
adult emerging in the spring, earlier in the South and later farther North. 
The eggs, varying in number from less than 500 to nearly 3,000 are now- 
laid on different parts of the food plants afid on weeds or even on the 
ground. They hatch in a week or less, according to the temperature, and 



THE LEPIDOPTERA 



271 



the larvse (Fig. 2786) begin feeding, at first on the surface of the plant 
but soon boring into it at some tender place. 

With cotton, injury is caused by eating out the squares and the more 
tender bolls. In the case of corn the first attack is by boring into the 
bud and eating down into the developing leaves. Later, the tassels are 
often injured before they open, and after the silk appears eggs are laid on 
this and the caterpillars which hatch from them bore into the ears of corn to 
varying distances, often entirely destroying the ears, particularly in the 
case of sweet corn. Tomatoes are injured mainly by the larvse boring 







Fig. 278. 



-Corn Ear Worm (Chloridea obsoleta Fab.) : a, adult moth; b, larva; d, pupa: all 
enlarged. {From U. S. D. A. Farm. Bull. 890.) 



into the green or partially ripened fruit, and in some cases by boring into 
the tips of the plants or eating the blossoms. With tobacco the larvae 
attack the bud leaves at the tip of the plant and later bore into the pods. 
Peaches, peas, beans, etc., are also sometimes injured and the average 
annual loss by the ravages of this pest in the United States has been esti- 
mated as over eighteen million dollars. 

There are several generations of this insect each year, four or five 
being produced in the far South and this number reducing northward 
until in the Northern States and Canada there is but one. The larvse 
vary greatly in color and markings and are most easily recognized by the 
nature of their work. When full-grown they are about an inch and a 
half long. 



272 APPLIED ENTOMOLOGY 

Control. — Late fall plowing to break up the earthen cells in the ground 
where the insects winter as pupse, provided the plowing is rather deep, 
is a helpful procedure. As the larvae feed for a short time on the surface 
of the plants before boring into them, the application of arsenate of lead 
at or just before this time, is advantageous. With the increasing num- 
bers in the later generations of the insect, fertilization, culture and any 
methods possible for hastening the maturity of the crop are desirable. 
Green corn is the preferred food plant of this insect and rows of corn 
planted in and near cotton fields, if in tassel and silk about the first of 
August will attract most of the moths, leaving the cotton much more free 
than otherwise. On corn itself, dusting powdered arsenate of lead onto 
the silks, as soon as these appear, seems to reduce the damage to quite an 
extent if applied at 3 or 4-day intervals while the silk is developing. 

In the Noctuidae are a number of species where some of the abdominal 
feet of the caterpillars are not functional or are absent, as a result of 
which these larvse travel like those of the Geometers or "inch worms" 
already described. Several of these species are occasionally injurious to 
cultivated plants. In most cases at least, such larvse can be controlled 
by the application of arsenate of lead. 

The Army Worms also are members of the Noctuidse, this name being 
given to the insects because of their habit of marching from place to place 
all together, like armies. They are periodically injurious insects, appear- 
ing in great abundance at times, but 
rarely troublesome for more than one 
season at a time in the same place. 

The Army Worm {Cirphis uni- 
punda Haw.). — This pest is probably 
a native of North America. It occurs 
over the entire eastern United States 
as far west as Kansas and Nebraska, 
Fig. 279. — Adult Moth of the Army and has been reported from the 
Z^rtr!;::^''''^''^^''^'''''' southwestern States and California. 

The adult moth (Fig. 279) spreads 
about an inch and a half, and is quite uniformly brownish-gray with a 
tiny white spot near the middle of each front wing and a rather dusky 
outer margin on the hind wings. The moths fly at night and are often 
attracted to lights. 

In what stage this insect passes the winter does not appear to have 
been conclusively proved, but it is probably as the partly grown cater- 
pillar hiding in rank, dense weedy growth. In late spring, at least, 
the nearly full-grown larvse have been found feeding on grasses primarily 
and then on small grain. The larvse mature quite rapidly, pupate in the 
ground and produce the moths in June, at least in the North. Eggs 
are now laid on grass and similar plants and hatch in 8 or 10 days 




THE LEPIDOPTERA 



273 



and the larva feeds for 3 or 4 weeks until about an inch and a half long. 
It is now a nearly naked caterpillar (Fig. 280), somewhat variable in 
color but generally rather 
greenish, with a broad dark 
stripe along its back with a 
fine, broken, white line along 
its middle, and a dark stripe 
along each side. 

Before this size has been 
attained all the food where 
these insects are, may have 
been consumed if the larvae 
are abundant, and in this case 
they march off in armies to 
find new feeding grounds, 
and it is these marching 
armies which usually attract 
attention in July or August. 
When feeding has been com- 
pleted they pupate in the 
ground and the moths emerge 
in September or October and 
probably lay eggs which soon 
hatch, the caterpillars thus 
produced, feeding to some ex- 
tent before winter. The 
spring-feeding generation ap- 
pears to be little noticed, the 
destruction seen being by the 
summer generation. 

When the caterpillars are 
abundant numerous flies re- 
sembling, but larger than 
house-flies, and called "ta- 
china flies," are usually 
noticed flying about the 
army. These are, nearly al- 
ways at least, parasites laying 
their eggs on the caterpillars. 
The maggots which hatch 
from these eggs bore into the 
caterpillars and feed upon and 
finally kill them. There are also several other insect enemies of the 
Army Worm. 




JiM. 



Fig. 280. — Army Worm Caterpillars feeding on 
corn. Natural size. {From Britton, Fourteenth 
Rept. Ent. Conn. Agr. Exp. Sta. 1914.) 



274 APPLIED ENTOMOLOGY 

Control. — If Army Worms are discovered before they begin their 
march, spraying all the plants where they are with a stomach poison 
is an effective treatment, or if the infested area is small, straw can be 
spread over it and burned. Once on the march, protection of any crops 
towards which the caterpillars are marching, either by destroying the 
insects or by preventing their reaching the crops, is the aim of any treat- 
ment. Poisoned baits (see under " Cutworms," page 276) may be used for 
this purpose, or where the ground over which the insects are marching 
is fairly smooth and firm, the use of a heavy roller is possible. A ditch 
dug across their line of march or around an infested area is often used, 
and a log dragged along in the ditch as the caterpillars become thick in it 
will kill multitudes. Food in a strip ahead of their line of march, sprayed 
with a stomach poison will result in the poisoning of those which feed 
there, and in some cases the caterpillars while marching can be reached 
and killed by a strong contact insecticide. 

The Fall Army Worm (Laphygma frugiperda S. & A.). — This insect in 
many ways resembles the true Army Worm. It has numerous common 
names such as the "grassworm," "overflow worm," "alfalfa worm," 
etc., and it is called the Fall Army Worm only in the Middle and Northern 
States, as it does not appear there before fall. 





Fig. 281. Fig. 282. 

Fig. 281. — Moth of Fall Array Worm (Laphygma frugiperda S. and A.), about natural 
size. (Modified from U. S. D. A. Farm. Bull. 7r2.) 

Fig. 282. — Full-grown Caterpillar of Fall Army Worm, somewhat enlarged. {Modified 
from U. S. D. A. Farm. Bull. 752.) 

This insect is probably a native of this country. While most destruc- 
tive in the South it may spread during the season far to the North, 
reaching the New England States, southern Wisconsin and south- 
eastern Montana, and extending westward to the Rocky Mountains. 

The moth (Fig. 281) spreads about an inch and a quarter. Its front 
wings are mottled gray, usually with a light spot near the tip, and the 
hind wings pearly white, edged with a rather narrow, dark line. It does 
not seem to be able to live over winter north of the southern parts of the 
Gulf States. The caterpillar (Fig. 282) feeds upon native grasses pri- 
marily, but when these are not sufficiently abundant it may attack 
grains, sorghum, alfalfa, clover, cotton and other crops. 

In what stage this insect spends the winter does not seem to have 
been positively determined, but it is probably the pupa. The eggs. 



THE LEPIDOPTERA 



275 




Fig. 283.— Dingy Cutworm {Fellia 
subgothica Haw.): a, moth, wings 
spread; b, larva (Cutworm); c, Moth, 
wings folded. All somewhat enlarged. 
(From U. S. D. A. Farm. Bull. 856.) 



from 50 to several hundred in number, are laid preferably on grass blades 

and in the South hatch in a few days. The caterpillars feed 2 or 3 weeks 

before reaching full size and are then very similar to those of the Army 

Worm. They then pupate for 10 to 14 

days in the ground, after which the adult 

moths emerge. Many of these moths 

now fly northward, often several hundred 

miles, before laying their eggs, and in 

this new location another generation is 

produced, the adults of this generation 

also flying northward to lay their eggs. 

In this way the northern part of the 

country becomes infested in the fall but 

frost puts an end to the development of 

these insects near their northern limits 

before more than one generation can be 

produced. Going southward, more are 

possible, and in the Gulf States there 

may be six in the course of a season. 
Where corn and cotton are grown the 

destruction caused by this insect is often 

very great, the caterpillars as they get large having voracious appetites. 

They usually feed more at night than during the daytime, and like the 

Army Worm, march to 
other places to find food 
when the supply where they 
are becomes exhausted. 

In general the methods 
used for controlling the 
Army Worm apply to this 
insect also. 

A number of other 
species of Noctuids have 
the habit of marching in 
armies when their food be- 
comes scarce. Their life 
histories and habits are for 
the most part quite similar 
to those of the two species 
already described, and con- 
trol methods for them are 
generally the same. 
Still another section of this family occurs, widely distributed, and 

causing much injury. The insects of this division are called Cutworms 

(Figs. 283 and 284) because of the habit of the larvse of feeding on the 




Fig. 284. — Cotton-boll Cutworm (Prodenia ornilho- 
galli Guen.): a, light form of Cutworm; b, dark form; 
dark form of Moth above; pale form below. All some- 
what enlarged. (From U. S. D. A. Farm. Bull. 890.) 



276 APPLIED ENTOMOLOGY 

stems of succulent plants at about the level of the ground and thereby 
either partially or entirely cutting them off at this point. Several 
hundred species have this habit and many kinds of garden and field 
crops suffer in this manner during the spring and early summer months. 
A few have the habit of climbing up the plants at night and feeding 
there, some distance above the ground. 

The moths are usually of medium size, spreading from an inch to 
about two inches, and are generally quiet colored, gray, brown or blackish, 
more or less mottled, streaked or banded on the fore wings while the 
hinder pair are nearly white and unmarked except for darker margins in 
some cases. Some species are more strongly marked, however, and have 
brighter colors. 

Most of these insects winter either as pupae or partly grown cater- 
pillars. In the spring the latter pass the day in the ground, coming up 
at night to feed. They are generally dull colored with rather faint spots 
and lines and without a hairy covering, and when full-grown will average 
an inch to an inch and a half in length. When feeding has been completed 
they pupate a few inches deep in the ground. Some species have one 
generation each year; others two. 

Control. — Late fall plowing to bring up and expose the insects to the 
fluctuating temperatures of the cold season and its rains, is a useful 
treatment, but other measures are also necessary. When Cutworm 
work is seen the use of a poison bait is desirable. For this purpose one 
good formula is: 

Larob For Small 

Quantity Gardens 

Bran 50 lb. or 1 pk. 

Paris green 2 lb. or 3^ lb. 

Cheap molasses 2 qt. or 1 pt. 

Oranges or lemons 3 fruits or 1 fruit 

Water 3 to 7 gal. or 4 to 6 qt. 

The second formula is for use where only a small quantity is desired. 

Mix the bran and Paris green together thoroughly, dry: add the 
juice of the fruit to some of the water and chop up the rest of the fruit 
finely and add this and the molasses. Now combine this mixture with 
the bran and Paris green and stir thoroughly, adding enough more 
water to finally produce a rather stiff dough. This can be used in 
gardens, placing about a teaspoonful close to the base of each plant liable 
to attack, but should be put on toward night so that it will not dry up 
in the sun and lose its attractiveness to the Cutworms. Fowls should 
be shut up while this treatment is being used, to prevent their feeding 
on the bait and being poisoned. 

Where large fields are to be treated, a modification of this formula 
is desirable, reducing the amount of water to a point where the mixture 
is dry enough to spread broadcast, yet wet enough so that each flake of 



THE LEPIDOPTERA 



277 



bran has been moistened by the molasses and fruit juice sufficiently to 
make it attractive, and also bears a little of the poison. The amount of 
water to add to obtain this condition must be determined by testing the 
mixture at intervals to see that the bran is dry enough to spread, and 
also that it has been able to take up the other materials. In any case the 
mixture should stand for several hours before use, to allow the bran time 
to take up the other constituents. The larger quantity given above is 
sufficient to spread broadcast over several acres. 

The size of the family Noctuida? and the abundance of its members 
in all parts of the country, as well as the various methods of feeding 
present in the group make it one of the most destructively important 
families of Lepidoptera in the United States. 

Famihj Arctiidae (The Tiger Moths) . — The Arctiids are mainly medium-sized 
moths, often brilliantly colored. Most of the group are not serious pests, but 
individuals, particularly in their larval stage, are often seen. Many of these 
caterpillars are quite densely and uniformly covered with long hairs and are 
sometimes called "woolly bears." One of them often seen crawling about in the 




Fig. 285. Fig. 286. 

Fig. 285. — Isabella Tiger Moth {Isia Isabella S. and A.), slightly reduced. (Original.) 
Fig. 286. — Hickory Tiger Moth (Halisidota carycB Harr.), natural size. {From 
Britton, Seventh Rept. Ent. Conn. Agr. Exp. Sta. 1907.) 



fall is covered with reddish-brown hairs at each end, and black ones in the middle, 
and is sometimes given the particular name "hedgehog caterpillar." The adult 
(Fig. 285), not often seen, is an orange-buff moth, its hind wings tinged with 
pinkish, and spreads a little over two inches. It is called the Isabella Tiger Moth 
(Isia Isabella S. & A.). Another caterpillar, the "salt-marsh caterpillar" {Estig- 
mene acrcea Dru.) has a blackish head and body, well covered with long, tufted, 
brownish hairs. The adult is about the size of the Isabella Tiger Moth, the male 
having white fore wings spotted here and there with black, while the female has 
all its wings white and spotted. The abdomen of both sexes is orange. The 
Hickory Tiger Moth {Halisidota caryce Harr., Fig. 286) is quite common in the 
northeastern United States and Canada, west to Minnesota and south to North 
Carolina and Ohio. The larvae, which occur in the summer and fall, feed on 
many kinds of trees and are sometimes rather injurious. At first they feed in 
company but during the latter part of their larval life they scatter. The full- 



278 



APPLIED ENTOMOLOGY 



grown larva (Fig. 287) is an inch and a quarter or more in length, covered with 
grayish-white and black hairs. Along the middle of the back is a row of tufts 
of black hairs and there may also be longer, slender black tufts or "pencils." 
The insect winters as the pupa under rubbish on the ground, and the moths 
emerge in late spring and early summer and are yellowish in color, the fore wings 
sprinkled with brown dots and two brownish streaks. These wings are rather 
narrow for their length, and somewhat pointed. The hind wings are nearly 

transparent and almost white. The moths 
spread about two inches. Control is by 
spraying with a stomach poison as soon 
as the work of the caterpillars is noticed. 

The Fall Webworm {Hyphantria 
cunea Dru.). — This insect is a pest on 
shade, fruit, and ornamental trees. 
It is found everywhere in the eastern 
United States and as far west as 
Montana and Texas. In the South 
and northward about to New York 
there are two generations each year 
and a correspondingly greater amount 
of injury than where one is the rule. 





Fig. 287. Fig. 288. 

Fig. 287. — Full-grown Caterpillar of the Hickory Tiger Moth, natural size. (From 
Britton, Seventh Rept. Ent. Conn. Agr. Exp. Sta. 1907.) 

Fig. 288. — Fall Webworm (Hyphantria cunea Dru.), about natural size. (Original.) 



The adult moth (Fig. 288) spreads about an inch, and in the north 
has pure white wings. Farther south black spots are present on them 
and this difference has led to the belief, still held by some persons, that 
there are really two species concerned. The winter is spent as the pupa 
in the ground, the moths emerging in the late spring and laying their 
eggs in clusters, often 200 or 300 in number, on the under side of the 
leaves. These hatch in about 10 days and the larvae pass together 
to the outer foliage of some branch, where they form a thin white web 
over the surface, feeding on the leaves enclosed within the web (Fig. 
289). As the caterpillars grow and consume this foliage, the web is 
extended to cover more leaves and by the time full size has been attained 
by the caterpillars, the web may be as large as a bushel basket. The 
full-grown larva (Fig. 290) is over an inch long, quite hairy but not 



THE LEPIDOPTERA 



279 



sufficiently so to conceal the body which is generally "pale-yellowish or 
greenish, with a broad, dusky stripe along the back and a yellow stripe 
along the sides; they are covered with whitish hairs which spring from 




Fig. 289. 



-Branch covered by web of the Fall Webworm. 
Bull. 139.) 



{From N. H. Agr. Exp. S(a. 



The head is black. The 




black and orange-yellow warts" (Packard) 
larvae pupate in the ground. 

Where there are two generations the moths appear in June or even 
earlier and the second generation moths develop early enough in the 
fall for the larvae from their eggs to become full- 
grown before the leaves drop. Where there is 
but one generation the webs appear the last of 
July and in August, and reach full size in 
September. 

Control. — There are several ways by which 
to check the ravages of this insect. When the 
webs first appear they may be stripped off by hand and the then 
small larvae crushed. Branches attacked may be cut off if the tree is 
of sufficient size not to be marred in this way. Spraying all around 
the tent with a stomach poison, standard formula, will poison the leaves 
next to be brought within the web by its further enlargement, and thus 
provide the caterpillars with poisoned food. 



Fig. 2 9 .—Full-grown 
larva of the Fall Webworm, 
natural size. (Original.) 



280 



APPLIED ENTOMOLOGY 



Family Ceratocampidae (The Royal Moths). — In this family are included 
several very large moths and a few smaller ones. The Regal Walnut Moth 
{atheroma regalis Fab.) may have a wing-spread of six or seven inches (Fig. 291). 
Its fore wings are rather dusky but the veins are lined with orange-red and there 
are numerous yellow spots. The hind wings are lighter, with some yellowish areas, 
and veins lined as in the other pair. The stout body is brownish-orange with 




Fig. 291. 



-Regal Walnut Moth {Ciiheronia regalis Fab.), about half natural size. 
Felt, N. Y. State Mus. Mem. 8.) 



{From 



narrow yellowish cross lines. The caterpillar (Fig. 292) which feeds upon various 
trees, is four or five inches long when full-grown and has a green body bearing 
numerous black spines and, just back of the head, a number of very long reddish 
spines bending backward and tipped with black. The head is red. The terri- 
fying appearance of this caterpillar has probably been the reason for calling it 




.Fig. 292.- 



-FuU-grown larva of the Regal Walnut Moth, slightly less than half natural size. 
(From Packard, Mem. Nat. Acad. Sci., IX, Part II.) 



"The Hickory Horned Devil." The insect is found from Massachusetts to Loui- 
siana, Texas and Missouri, but is not very abundant and therefore does little 
injury. It feeds on the black walnut, butternut, hickory and a number of other 
trees, and has once or twice caused some damage to cotton. It winters as a pupa 
in the ground. 



THE LEPIDOPTERA 



281 



Another large moth belonging here is the Imperial Moth {Basilona imperialis 
Dru., Fig. 293) which has about the same distribution as the Regal Walnut Moth. 
The adult often spreads six inches and is yellow, with lilac or purplish-brown 




Fig. 293. 



Imperial Moth (Basilona imperialis Dru.), slightly more than half natural size. 
(From Felt, N. Y. State Mus. Mem. 8.) 



areas or bands and spots. The caterpillar (Fig. 294) is green (or brown sometimes), 
from three to four inches long when full-grown, rather well covered with long, 
white hairs, and has two pairs of rather stout, upward projecting tubercles or 
horns behind the head. It feeds on quite a list of trees including some of the 




Fig. 294.^Fu11- 



;rown larva of Imperial Moth, somewhat reduced. 
Packard, Mem. A'at. Acad. Sci. IX, Part IL) 



(Reduced from, 



evergreens, and pupates in the ground during the winter. Like the last species 
it is rarely if ever abundant enough to be of economic importance. 

Several insects in this family are quite common at times and locally may be 
numerous enough to cause some injury to oaks, maples and other trees they feed 
upon, but their presence is noticed for only a year or two at a time. 



282 



APPLIED ENTOMOLOGY 









^ 


^^ /-^l^^l^ 






^i^^ ^ 


iM^ 


^. 




.^bBH^B '^T^^^^^i^**^^ ' 


Wk 


1^ 


^^^ 


p.!^', 


' A\ 






^^' 


1 


■ ^ 


^1 


p 



Fig. 295. — Cecropia Moth {Samia cecropia L.), slightly over half natural size. (Original.) 




Fig. 296. — Polyphemus Moth {Telea polyphemus Cram.) , about three-quarters natural size. 

(Original.) 



THE LEPIDOPTERA 



283 



Family Saturniidae (The Giant Silkworms). — In this family belong most of 
the common, very large moths found in North America. Though their size 
and that of their caterpillars attracts attention, these insects are of little economic 
importance as the number of eggs laid by an individual is not very large and 
they are generally well scattered so that few larva? are often found on any one 
tree. If the silk of their cocoons could be utilized they would become industrially 
important, but the thread is frequently broken so that reeling it is difficult and 
expensive. 

One of the more common species in this family is the Cecropia Moth {Samia 
cecropia L.), a very large, brownish-gray insect (Fig. 295) with a whitish, crescent- 
shaped spot partly shaded with brown, near the center of each wing. Outside 
this spot a whitish line crosses the wing and the outer margin is more or less 
broken by black spots on a whitish ground. The abdomen is brown with white 
crossbands. The caterpillar (See Fig. 21), which when full-grown is from three 




Fig. 297.- 



-Male Promethea Moth (Callonamia promcthea Dru.'), about two-thirds natural 
size. (Original.) 



to four inches long, is green with tubercles along its back, two pairs near the 
head being coral red and the others yellow except the first and last pair which are 
blue. The insect feeds on many kinds of plants, including some fruit and shade- 
trees. The moths appear in late spring, the larvae feed during the summer, and 
in the fall spin rather dense cocoons on the twigs of the trees, in which they 
pupate and pass the winter 

A rather similar moth, though usually a little smaller, is the Polyphemus 
Moth {Telea polyphemus Cram.), with brown wings crossed near the outer 
margin by a blackish band (Fig. 296). The front wing has a transparent "eye" 
spot with a yellow margin, around which is a black line. The hind wing has a 
somewhat similar spot, but the black around it covers quite an area, particularly 
toward the base of the wing. The caterpillar is green with a yellow, oblique 
line on the side of most of the segments of the abdomen and it feeds on many 
fruit and forest trees. The cocoon is spun among leaves on the ground. 

Somewhat smaller, spreading about four inches, is the Promethea Moth {Coll- 
osamia promethea Dru.). The male moth (Fig. 297) is dark brown except toward 



284 



APPLIED ENTOMOLOGY 



the outer margin of the wing where the color hghtens somewhat outside a whitish 
cross line, and the outer margin is light-grayish with fine brown lines. Near 
the apex of the front wing is a black "eye" spot, margined on the inner side with 
blue. The female (Fig. 298) is brown with a triangular, white spot near the 
center of each wing, a short distance outside of which the brown ends abruptly 
in a very irregular edge against white which shades off into brown again. 
The outer margin is as in the male and the eye spot is also present on the 
fore wing. 

The caterpillar is pale green with very small black tubercles in pairs 
above, except two pairs not far behind the head, which are coral-red and 
larger than the others, and a yellow one above, near 
the hinder end. The larvae feed on many kinds of 
trees and shrubs, appearing to prefer the sassafras, 
wild cherry and ash, and when through feeding, each 
selects a leaf, the petiole of which it spins around, 
fastening it in this way to the twig on which it 
grew, so that it cannot drop off in the fall. It then 





Fig. 298. Fig. 299. 

Fig. 298. — Female Promethea Moth, about two-thirds natural size. (Original.) 
Fig. 299. — Cocoon of the Promethea Moth, natural size. (From Britton, Thirteenth 
Rept. Ent. Conn. Agr. Exp. Sta. 1913.) 

forms its cocoon with the leaf as a partial wrapping, drawing the edges around 
the cocoon (Fig. 299). Here, in this hanging cocoon, swaying in the winds, 
the insect passes the winter. 

The Japanese Silkworm Moth {Philosamia cynthia Dru.) was introduced 
into the United States in a futile attempt to use its cocoons for silk. Some 
of the insects escaped and this species is now occasionally captured in Southern 
New England and the Middle Atlantic States. The moth (Fig. 300) spreads about 
six inches and is of a rather rich shade of brown. On each wing is a large white 
crescentic spot, edged in front by a black line, and a white band, shading on its 
outer side into lilac, then into brown, crossing the wing, touches the outer angle 
of the crescentic spot. On the front wing a white band runs from the inner 
angle of this spot to the body and another to the costa or front margin of the 
wing. On the hind wing a similar band curves across about halfway between 



THE LEPIDOPTERA 



285 



the crescent spot and the base of the wing. The caterpillar feeds on the leaves 
of the Ailanthus tree and has tufts of white hairs on its body. The cocoon 
is made within a partly rolled leaf as in the case of the Promethea Moth. 

One of the largest insects in this family is known as the Luna Moth {Tropcea 
luna L.). Its body is densely covered with white hairs giving it a woolly appear- 
ance, and its wings are pale green, with more or less complete purplish margins, 
particularly strong along the costa of the fore wing (Fig. 301). In the front 
wing is a rather oval "eye" spot connected by a purplish band with the costa. 
The hind wing also has an "eye" spot, more circular in outline, shaded with 
darker on the side nearest the body, and the wing itself extends backward into a 
long, narrow tail. The green caterpillars, between two and three inches long when 




Fig 300.- 



- Japanese Silkworm Moth (Philosamia cynthia Dru.), about two-thirds natural 
size. {Original.) 



full-grown, feed upon a number of kinds of trees and pupate among leaves on the 
ground in the fall. The insect is found from Canada southward throughout the 
United States east of the Rocky Mountains. 

One of the smaller, very common moths of this group is the lo Moth {Auto- 
meris io Fab.) which spreads between three and four inches (Fig. 302). The two 
sexes differ in color, the ground color in the male being yellow, while in the fe- 
male that of the fore wings is purplish-red. The yellow of the male fore wing has 
irregular spots and a wavy line of brownish: in the female the ground color is 
broken by irregular shadings and a lighter wavy line. The striking feature of 
the hind wing in both sexes is a large, circular, bluish "eye" spot with a white 
dot forward of its center. The bluish shades into black outside, and is surrounded 
by the yellow ground color. Between the eye spot and the outer margins are a 
black line and a dull-rose band, and the base and hinder margin are dull rose. 



286 



APPLIED ENTOMOLOGY 



The caterpillar is about two inches long when full-grown, with a rather wide 
reddish-brown stripe edged with white below, on each side of the body. It 
has many spines which branch, the branches being tipped with black. Touching 




Fig. 301. — Luna Moth (Tropcea luna L.), slightly over half natural size. 

N. Y. State Mus. Mem. 8.) 



(From Felt, 



the caterpillars produces a nettling of the skin, due to poison conveyed through 
the tips of the spines. The larvae feed on fruit, forest and shade-trees and usually 
make their cocoons among leaves on the ground. 




Fig. 302. — Female lo Moth {Automeris io Fab.), about two-thirds natural size. 
Felt, N. Y. State Mus. Mem. 8.) 



(From 



There are quite a number of kinds of Giant Silkworms, the family being 
represented in all parts of the country. One generation a. year; the moths appear- 
ing earlier or later in the spring according to the length of the season; the larvae 



THE LEPIDOPTERA 



287 



feeding during the summer; and pupation in the fall, with the winter spent in 
this stage, appears to be the general rule, though with some exceptions, for most 
if not all of the species. 

Family Sphingidae (The Hawk Moths). — This large and widespread 
group of insects has long and rather narrow fore wings and its members 
have a strong flight. Most of them are of quite large size (Fig. 303) and 
fly chiefly at dusk, visiting flowers for the nectaf, upon which they feed. 
They do not alight on the flower but hover over it, running the tongue, 
which is often much longer than the body, into the nectary. The body 




Fig. 303. — Hawk Moth {Sphinx chcrsis Hbn.), natural .size. {Original.) 



is usually rather stout, spindle-shaped, and it and the wings are often 
beautifully colored with combinations of black, gray, olive, tan and rose 
or pink. The antennae are large, usually somewhat thickened near the 
middle, and the end is in some cases curved a little, like a hook. 

The larvae feed upon the leaves of various trees and other plants. 
They are naked; generally green, though frequently of other colors, and 
in the former case often have oblique white streaks on the sides of the 
body and a long horn projecting upward and backward from the upper 
side near the hinder end. Some when full-grown, may be two or three 
inches long. Pupation is usually in earthen cells underground, though 
some form partial cocoons of leaves and silk on the surface. In some 
species the tongue at the time of pupation is not enclosed by that part 
of the pupal skin which covers the body, but by a separate portion which 
joins the remainder at the front of the head and touches the body about 
halfway back, which makes it resemble the handle of a pitcher or jug 
in its relation to the pupa as a whole. 



288 



APPLIED ENTOMOLOGY 



A few species have their wings only partially covered by scales. 
These are among the smaller species and they fly during the day (Fig. 
304). 

Of the various species of Hawk, or Humming Bird Moths as they are 
sometimes called, only two or three are usually 
of any great economic importance. 

The Tobacco and Tomato Worms. — There 
%VS,^^ ^^^y^ are two closely related Hawk Moths whose 

^^llii^ larvse feed on tobacco and tomato leaves. 

^^J fJsK^ b^ One of these is known as the Northern 

Tobacco (or Tomato) Worm (Phlegethontius 
quinguemaculata Haw.) and the other as the 
Southern Tobacco Worm (Phlegethontius sexta 
Johan.). The former is present nearly every- 
where in the United States: the latter from 
Massachusetts southward, and westward to 
the Pacific Coast. 
The adult is a moth (Fig. 305) spreading from four to five inches, 
but in the Northern Tobacco Worm the color of the fore wings is ashy- 
gray and the abdomen has a row of yellow spots, usually five in number 




Fig. 304. — Day-flying Hawk 
Moth (Hemaris diffinis Bdv.), 
about natural size. (Original.) 




Fig. 305. — Northern Tobacco Worm Moth (Phlegethontius quinquenaculata Haw.), natural 
size. (From Bntton, Sixth Rept. Ent. Conn. Agr. Exp. Sta. 1906.) 



on each side, while in the Southern Tobacco Worm the fore wings are 
brownish-gray and there are usually six yellow spots on each side of the 
abdomen. 



THE LEPIDOPTERA 



289 



The life history in both species is quite similar. Winter is passed 
as a pupa (Fig. 306) in Iho ground and in these insects the tongue 




Fig. 306. — Pupa of the Southern Tobacco Worm (left) and of the Northern Tobacco 
Worm (right), natural size. Note difference in length of the tongue case. {From 
Britton, Sixth Rept. Ent. Conn. Agr. Exp. Sta. 1906.) 




Fig. 307. — Full-grown larva of Southern Tobacco Worm, natural size. 
Sixth Rept. Ent. Conn. Agr. Exp. Sta. 1906.) 



(From Britton, 



has a separate case in the pupa. The moths appear in the spring 
and lay their eggs singly on the leaves of their food plants, and the 



290 



APPLIED ENTOMOLOGY 



caterpillars feed for 3 or 4 weeks, becoming three or four inches long, 
green or sometimes brown in color. In the Northern Tobacco Worm 
each abdominal segment is marked on the side by an oblique greenish- white 
stripe joining a similar horizontal one at its lower end, forming a series 
of whitish Vs. On the hinder end of the body above, is a projecting 
green horn with black sides. The larva of the Southern Tobacco Worm 
(Fig. 307) has only the oblique bands and the horn is usually reddish. 
In the northern part of the range of these species there is one generation 
a year. Farther south, two seems to be the rule, while in the Gulf 
States three or four are claimed to occur. 

Control. — Hand picking is a frequent method of control where the 
larvae are not abundant. Spraying when the caterpillars are first seen, 
with arsenate of lead, standard formula, has proved effective. Applied 
as a dust it has also given good results, but this material either as a spray 
or as a powder should not be used on tomatoes after the fruit is half 
grown. 

The remaining families of Lepidoptera to consider are those of the 
suborder Rhopalocera, or butterflies. Most of the insects in this section 
are rarely of much economic importance, their larvse feeding chiefly on 
plants not utilized in any way as food. Occasionally some species may 
cause local injury, but only a few need special consideration from this 
standpoint. 





Fig. 308. Fig. 309. 

Fig. 308. — Skipper Butterfly {Epargyreus tityrus Fab.), natural size. {Original.) 
Fig. 309. — Little Copper Butterfly {Heodes hypophleas Bdv.), about natural size. 
(Original.) 

Family Hesperiidae (The Skippers).— These are rather small butterflies 
which have a curious "skipping" style of flight. They are most frequently 
black, or yeflow and black in color, often with silvery spots or streaks (Fig. 308). 
The larvffi in this family have heads much larger than the part of the body next 
behind, making them easy to recognize. One of the larger members of this 
group, found in the South feeds as a caterpillar on the bean, and is known as the 
Bean Leaf-roller. 

Family Lycaenidse.— In this group belong the Uttle blue butterflies spreading 
in most cases at least, less than an inch; similar sized dark-brown butterflies; and 
others which are of a red or coppery color (Fig. 309), with black spots. Many 



THE LEPTDOPTERA 



291 



of these insects are very common but are of no importance economically. One 
species here departs from the general rule as to the food of Lepidoptera, its larva 
being carnivorous and feeding on plant lice. Unfortunately it is not common 
enough to be very beneficial. 

Some of the species in this family have more than one generation each year 
and the adults of the two generations are so different that until one kind was 
bred from eggs laid by the other they were supposed to be different species. 
Difference in color, markings or both, may therefore be correlated with the season 
of the year, and insects having two different forms according to the season, 
present cases of what is called seasonal dimorphism. 




Fig. 310. — The Monarch (Danaus archippus Fab.), natural size. (Original.) 



Family Danaidae. — This small family is of interest in the United 
States mainly because it includes one of our largest and widely distributed 
butterflies, the Monarch {Danaus archippus Fab.). This is common 
in nearly all parts of the country and has a striking way of sailing about 
in the air. The ground color of the wings is tawny brown marked 
with black lines along the veins, and broad black borders containing 
white spots (Fig. 310). The caterpillars feed upon milkweed and are 
greenish-yellow with black cross-bands and a pair of soft, fleshy projec- 
tions on the back a little behind the head, and another pair not far from 
the hinder end of the body. The pupa (chrysalis) is usually attached to 
the plant and is about an inch long, stout, bright green with golden dots. 

Though the Monarch breeds in the Northern States during the 
summer, it appears to come from the South each spring, and in the fall 
multitudes often gather and fly southward together. Whether they 



292 



APPLIED ENTOMOLOGY 



succeed in reaching climates where they can successfully winter is perhaps 
questionable, but if not, others at least, make their way North each 
spring. 

This insect is practically free from attack by birds, probably because 
it is able to produce a disagreeable odor. 

Family Nymphalidae.^This large family includes many familiar 
forms, most of them large or of at least fair size. Their fore legs have 
been reduced so much they they are no longer used but are carried 
folded up against the thorax. 

Several of the common species in this group are found in Europe 
as well as in this country and a few occur nearly everywhere in the 
world where food and temperature permit their existence. The larvae 
of some species feed on the currant, gooseberry and hop in the list of 
cultivated plants, but are not often important pests. 





^^fe^ 


\ 


\^^ -^ 


1'-^ 



Fig. 311. — The Viceroy (Basilarchia archippua Cram.), natural size. {Original.) 

In one section of the family the insects are usually black with blue 
or green, and occasionally red spots, and one or two species have a white 
band across the wings. One of this group, however, differs greatly in 
color from all the rest of its relatives, being reddish-brown with black- 
lined veins, black wing borders enclosing white spots, and so closely 
resembling the Monarch that it has been called the Viceroy (Fig. 311) 
It differs from the Monarch, to the eye, however, by the presence of 
a narrow black band across the hind wings and by its somewhat smaller 
size. 

This radical departure in color and pattern of this insect from that 
of all its near relatives is believed to be because this group is one freely 
attacked by birds for food, while the Monarch, perhaps because of a 
disagreeable odor, escapes. Any imitation which would deceive the 
birds, would accordingly protect insects possessing it and enable them 



THE LEPIDOPTERA 



293 



to avoid destruction. How such a change could be rapidly developed, 
however, to such a degree as to enable its possessors to benefit by it, 
has not been satisfactorily explained, and if it were not so developed 
the individuals in which the change began could hardly differ enough 
from their former condition to escape. Here remains one of the unsolved 
problems of insect life. 

Family Satyridae (The Satyrs). — The insects belonging in this family are of 
medium size, and nearly all have gray or brown wings with spots more or less 
resembling eye spots (Fig. 312) . They are common near the edges of woods and 
sometimes drift out into the fields. One species is found only on the tops of the 
White Mountains in New Hampshire and on the higher Rocky Mountains. 
How these colonies became so widely separated is a question, though explanations 
for it have been suggested. 




Fig. 312. — SatjT Butterfly {Cercyonis alope Fab.), natural size. {Original.) 

Family Pieridae. — In this family belong the medium sized or small 
yellow butterflies of various shades and the white ones, common in all 
parts of the country. About 50 kinds occur in the United States and 
some of them are occasionally, and others almost always, injuriously 
abundant in one place or another. 

The Imported Cabbage Butterfly {Pontia rapce L.). — This insect, a 
native of Europe, appears to have reached Quebec about 1859. It spread 
rapidly and ten years later had reached Massachusetts. Other specimens 
arriving at New York and Charleston, N. C, also estabhshed centers 
from which the insect spread in all directions, and it is now found nearly 
everywhere in the United States. 

The adult (Fig. 313a) spreads a little less than two inches. Its wings 
are white, the tip of the front wing grayish. In the male there is a black 
spot near the center of the front wing and one on the front margin of 
the hind wing, while in the female the front wing has a second black 
spot behind the other. 



294 



APPLIED ENTOMOLOGY 



The insect passes the winter as a pale brown chrysahs (Fig. 313d) 
about three-quarters of an inch long, attached in some protected place. 
The adults emerge in the spring and lay their eggs singly (Fig. 3136) 
on the leaves of cabbage, cauliflower, mustard, nasturtium and other 
plants of the family Cruciferse, and about a week later the caterpillar 
hatches and begins to feed. At first it is pale green, but when full- 
grown, after about 2 or 3 weeks, is a soft, velvety-green, and about an 
inch long (Fig. 313c). At first it feeds on the under surface of the 




Fig. 313. — Cabbage Butterfly {Pontia rapce L.) : a, adult, slightly enlarged; b, egg, 
from side and from above, considerably enlarged; c, caterpillar, somewhat enlarged; d, 
chrysalis, somewhat enlarged. {From U. S. D. A. Farm. Bull. 856.) 

leaf, but after growing, eats holes through and may leave only the veins. 
It often bores into the forming heads also, in search of more tender food. 
It feeds for from 2 to 3 weeks, then pupates for a rather shorter period, 
at the end of which time the adult emerges and lays eggs for a second 
generation. There are usually two or three generations in the Northern 
States and as many as five or six in the South. 

Where these insects are abundant they cause considerable injury, 
not only to the leaves but by boring into the heads, reducing their value. 

Control. — Spraying with a stomach poison, preferably arsenate of 
lead, a little stronger than the standard formula, as soon as the cater- 
pillars appear in the spring, is a successful treatment, but as the spray 
tends to run off the smooth leaves of the plants, the addition of. a little 
soap as a "sticker" is desirable. If the larvae of the first generation 
are killed for the most part by this, later applications will generally prove 
unnecessary. In some cases the poison is dusted on instead of sprayed. 



THE LEPIDOPTERA 



295 



If treatment is needed after the heads are half grown, they may 
be dusted with pyrethrum, though the danger of poisoning them by the 
use of arsenate of lead is practically none. 

A native cabbage butterfly closely resembling the last, was formerly 
common in the North, but appears to have suffered from competition 
with its imported rival. A southern native species has also become 
somewhat reduced in abundance, but less so than the northern one. 




Fig. 314. — Male Sulfur or Yellow Butterfly {Eurymus philodice Godt.)> natural size. 

(Original.) 

The common sulfur-yellow butterflies (Fig. 314) with more or less of black 
markings on their wings are for the most part, feeders on clover in their larval 
stages. One of them, the Alfalfa Caterpillar (Eurymus eurytheme Boisd.) is 
frequently a pest on alfalfa. It occurs everywhere in the United States west of 




Fig. 315. 



-Alfalfa Butterfly (Eurymus eurytheme Boisd.). about 1^^^ times natural size. 
(From U. S. D. A. Bull. 124.) 



the Allegheny Mountains and has been taken occasionally along the Atlantic 
Coast, but is chiefly of importance in the Southwest. 

The adult (Fig. 315) spreads about two inches and its wings are orange- 
yellow with black outer borders ; a black spot in front of the center of the fore 
wing and two reddish-orange spots which touch each other, near the center of 



296 



APPLIED ENTOMOLOGY 



each hind wing. In the female the black wing border has yellow spots in it. 
Sometimes the orange color in the female is replaced by whitish. The cater- 
pillar is brown at first but later becomes dark-green with a white stripe on each 
side (Fig. 316). Alfalfa, clovers, vetches and other legumes are fed upon. 
The number of generations seems to vary in different parts of the country 
from two in the North to six or possibly more, in the far South. The colder, or 




Fig. 316. — Caterpillar of the Alfalfa Butterfly, about three times natural size. {From U. 

S. D. A. Bull. 124.) 

in the Southwest, the dry months may be passed either as larva, pupa or adult. 
Treatment is by cultural methods such as pasturage, or early and close cutting of 
the crop, followed if necessary by rolling or brush dragging. 



The spreading of an insect introduced into a country is always of 
interest, even if no financial factor is involved, and several of the species 
considered in this chapter supph'^ good examples of this. Its method of 
introduction; its establishment; the rapidity with which it spreads, and 
the final limits of its distribution, are all topics for investigation. 

In the case of the Gypsy Moth its introduction was apparently inten- 
tional, though it was far from the plan of the scientist who brought it to 
this country that it should escape. It is stated that this scientist had in 
mind testing the silk-producing possibilities of various Lepidoptera and 
imported a number of species for that purpose. Unfortunately in some 
way, some of the Gypsy Moth specimens escaped and as he could not 
find them, he issued a notice calling attention to the fact, and warning 
the public of the possible menace they might become. 

The Brown-tail Moth appears to have been brought to this country 
as a winter tent containing young caterpillars, on an importation of 
roses from Europe. This occured before the inspection of nursery stock 
imported into this country was required by law. How the Cabbage 
Butterfly arrived, is not known, but it was probably the chrysalis on 
-some material brought as freight. 

It is evident that in any case, either an adult female able to deposit 
fertile eggs, or else several individuals at least, in some early stage, 
must be imported at about the same time, if the species is to obtain a 
start. Then with an individual ready to lay its eggs, suitable food 



THE LEPIDOPTERA 297 

plants for its young must be found. There can be no doubt, in theory 
at least, that there have been many cases in the past where failurie to 
succeed in this has resulted in the failure to establish themselves, of 
many species which would have been serious pests. 

Once started, however, even in a small way, an increase in numbers 
and in distribution becomes possible. If some of the insects, however, 
were parasitized and the parasites escaped, as well as those not so affected, 
the spread might be checked because of the small number of the pests 
which would not be found by the parasites. 

The spreading of a species from the point where it starts, has been 
aptly compared to that of a ripple caused by throwing a stone into water, 
which passes out in every direction on its surface. Such a spread will 
extend as far as the insect can find food on which it can live and a tem- 
perature and humidity under which it can survive. It follows that for 
many insects adapted to northern climatic conditions, a point will be 
reached in its southward spread where the temperature and humidity are 
such as to prevent its going farther. A lofty and continuous mountain 
range may, by producing such conditions, also prove a barrier to farther 
extension in that direction, even though beyond the range a favorable 
climate may again be found. Absence of any food upon which an insect 
can live will also put an end to distribution in that direction, and a pest 
adapted to the moist climate of the Eastern States may find itself unable 
to establish itself in arid regions. The rapidity with which it spreads 
appears to be determined by its fecundity, power of flight in many cases, 
and food supply, at least generally; an insect having a high rate of in- 
crease, abundant food, and strong in flight sometimes spreading several 
hundred miles in a year.- The much larger area to the north and north- 
east of Boston than to the south and west, now occupied by the Brown- 
tail Moth appears to be due, in part at least, to strong southwesterly 
winds while the moths are flying. 

Study of these and other factors involved, shows that northern insects 
as they spread southward are found chiefly at least, on higher land. One 
living at near the sea level in the Northern States will generally be found 
in the mountains in the South, and if it extends into Mexico it will there 
occur only on the higher Cordilleras, gaining by its elevation the lower 
temperature it has lost by its change of latitude. 

Thus we find that with sufficient information at hand, the distribution 
of many insects can be mapped, and that there is a division of the country 
into regions, the insects of one region rarely spreading far beyond its 
limits, and then only forming outposts of the species. 

It is true that some species are less affected than others by these 
conditions. The Monarch Butterfly, the House Fly and many others 
appear to be able to live under wide differences of temperature, humidity 
and the other factors concerned. As a whole though, an insect will 



298 



APPLIED ENTOMOLOGY 



spread within certain limits, but only within these, and this applies to 
other animals and to plants as well. 



Family Papilionidae (The Swallow-tails). — The butterflies of this 
group are nearly all large, and with a backward-projecting lobe or 
tail on the hind wing. One species or another may be seen in almost 
every part of the country but they rarely do much injury, feeding for the 
most part on plants of little importance. The Black Swallow-tail 
Butterfly {Papilio polyxenes Fab.) is probably the most important species, 
as it occurs all over the United States and feeds on celery, carrots, par- 
snips and other plants. 








5>.:'iliu\t'if/^Sii// 



Vf/>; 



Fig. 317. — Celery Butterfly {Papilio polyxenes Fab.): a, full-grown caterpillar; b, 
head of same showing osmaterium extended; c, male butterfly; d, outline of egg; e, young 
larva; /, chrysalis. All about natural size except d, which is much enlarged. {From U. 
S. D. A. Farm. Bull. 856.) 



The butterfly (Fig. 317c) spreads between three and four inches, and 
its wings are black with two rows of yellow spots crossing each wing, with 
blue shadings between the two rows on the hind pair. There is also a 
black spot surrounded by orange on the outer part of the hinder margin 
of the hind pair. In the male the inner row of yellow spots becomes a 
band on the hind wing. 

In the South the butterflies winter over, but in the North this period is 
spent as the pupa. Eggs are laid singly on the leaves of the food plants, 
and hatch in about 10 days. The caterpillars feed for from 10 days to 
several weeks, then form their chrysalids (pupae) on some part of the plant 
(Fig. 317/) and in from ten days to 2 weeks more the adult butterflies 
emerge. There are two generations in the North and more in the South. 



THE LEPIDOPTERA 299 

The caterpillar when full-grown (Fig. 317a and 6) is about two inches 
long, green with a black cross band on each segment, which may enclose six 
yellow spots or may fail to close these in on the front side of the band. 
Just back of the head is an opening out of which a soft, widely forked 
horn can be protruded when the insect is distributed. Such structures 
are called osmeteria and give off a disagreeable, pungent odor, and are 
probably to drive away enemies which may attack them. 

This insect is rarely if ever important enough to call for any control 
other than destroying the larvae by hand, though in most cases spraying 
with a stomach poison would be entirely effective if such a treatment were 
needed. 

A similar species present on the Pacific Coast, has the same habits. 



CHAPTER XXX 




THE MECOPTERA 

The Mecoptera is a small order of insects, both in numbers and in the 
size of its members. The adults usually have wings which are mem- 
branous, long, and generally narrow, with numerous veins. In a few 
cases, however, they are reduced or even rudimentary. The head is 
elongated on its underside, forming a sort of beak or rostrum, at the end 
of which are the chewing mouth parts (Fig. 318). In the males of one 
genus the terminal segments of the abdomen are drawn out and curl up- 
ward, suggesting the position of the end of the body in the scorpion, and 
from this the common name ''Scorpion Flies" has been applied to the 

order, though some of its members do not 
have this character. The larvse considerably 
resemble small caterpillars. 

The distinctive characters of the order 
are: 

Insects which when adult nearly always 
have four meynhranous wings, long and narrow 
and with numerous veins: head prolonged 
downward forming a beak, bearing chewing 
mouth parts at its end. Larvae more or less 
caterpillar-like. Metamorphosis complete. 

Mecoptera occur in nearly all parts of the 
world but nowhere appear to be very abundant. 
They seem to prefer to live in places having rank 
growth, and in low, damp woods, and are apparently carnivorous both 
as larvse and adults. A few species are found on snow during the winter 
months and are wingless or nearly so, but most of the group have wings 
longer than their bodies and fly quite well. The eggs are usually laid 
in masses in the ground and the larvse live in burrows in the ground, 
coming out to feed. They have legs supporting the abdomen and these 
are more numerous than in caterpillars. As far as known they pupate in 
earthen cells in the ground. 

The adults certainly feed upon other insects: larvse in confinement 
can be fed upon meat, but their natural food is probably any animal 
material they can obtain. Under such circumstances, these insects 
must be regarded as being, at best, of little economic importance. Fossil 
forms belonging to the Mecoptera have been discovered in different parts 
of the world. 

In a general way this order appears to have the Diptera, Trichop- 
tera and Lepidoptera as its nearest relatives. 

300 



Fig. 318. — Adult Meeopteron 
(Panorpa nuptialis G e r s t . ) 
natural size, showing beak pro- 
jecting downward from the 
head, on the end of which are 
the mouth parts. {Original.) 



CHAPTER XXXI 
THE DIPTERA 

The Diptera or Flies are small insects, the largest species known being 
slightly more than two inches long, but the majority are much smaller, 
and many are almost microscopic. The flies as a group are distinguished 
from other insects by the presence of only one — the front— pair of wings, 
attached to the mesothorax. Sometimes these are absent, the insect 
being entirely wingless, but there are only a few such cases. The hind 
wings have been transformed into a pair of curious structures known as 
hal teres. They are small and each resembles a sort of knob joined to the 
body by a stalk, usually slender, and variable in length. They are 
believed to have special functions but what these are is far from settled. 

The wings are usually transparent though sometimes smoky or other- 
wise colored, and in some instances scales are present either along the 
veins or elsewhere, and in one family they entirely cover both the body 
and wings. The veins are usually quite numerous but often show a 
tendency to unite toward the outer margin of the wing, forming closed 
cells in this way as well as by the more usual method with cross veins. 
In some families, the veins are very few and sometimes several appear 
only as faint traces. The hinder margin of the wing not far from its 
attachment to the body frequently has a notch called the axillary incision 
or sinus, and the membrane from here to the base may form one lobe, 
or by other incisions consist of two or even three lobes. The one nearest 
the base in some instances appears to become enlarged and lie over the 
base of the halter, often partly or entirely concealing this structure from 
above. 

The head of the fly is connected with the thorax by a small neck which 
permits considerable rotation. Much of its surface is occupied by the 
very large compound eyes which frequently meet above, particularly in 
the males. Between the two eyes, or behind their point of meeting, 
are usually three ocelli on the top of the head. 

The antennae vary greatly. They may consist of as many as 16 
segments or as few as three, in the latter case a bristle, frequently feathered, 
being often present, joined to the outer segment. 

In one section, a crescent-shaped cleft occurs above the attachment 
of the antennae to the head, curving downward on each side. This slit 
is called the lunula, and at the time when the fly escapes from its pupa 
case a large, bladder-shaped structure is pushed out through this from 
the inside of the head, and pressing against the end of the case, forces it 
off, enabling the fly to escape. Later, this structure which is called the 
ptilinum is drawn back into the head. 

301 



302 



APPLIED ENTOMOLOGY 



The mouth parts of flies are for sucking, and in some cases for piercing, 
also. True "biting flies" do not exist, the "bite" being really caused by 
the plunging of the sharp-ended, piercing mouth parts into the object 
attacked. There seems to be little doubt that the mouth parts of flies have 
been derived from ancestors with chewing structures, but the changes 
have been so great that to identify the different pieces with the corre- 
sponding ones of chewing insects is very difficult, and different views on 
this have been advanced by students of the subject. 




Fig. 319. — Mouth parts of A, a Tabanid; B, a mosquito: a, antenna; au, compound 
eye; hp, hypopharynx; Ibr, labrum; md, mandible; nix, maxilla; mxo, labium; oc, ocellus; 
pm, maxillary palpus. {Modified from Laug's Lehrhuch.) 

Without going into details, it may be stated that in the more typical 
fly mouth parts there are six bristle-shaped structures enclosed by a 
sheath, and one pair of segmented palpi (Fig. 319). The sheath is 
generally regarded as representing the labium or hinder lip, while the 
bristles represent the front lip or labrum, the tongue or hypopharynx, 
the two mandibles and the two maxillae. At the outer end of the sheath 
is a pair of lobes, often large, and these are considered as the labial 
palpi, leaving the segmented pair to represent the maxillary palpi. 
In some cases, the surfaces of the lobes regarded as labial palpi are 
roughened and adapted to the rasping of surfaces. Bringing together 
certain of the bristle-like mouth parts forms two tubes, or, in some cases, 
grooves more or less completely closed, through which fluids can be 
drawn into the body, and saliva be led into the wound made by the 
tips of the bristles. Solid food is utilized only by first dissolving it in 
saliva. 



THE DIPTERA 303 

The thorax, though composed of three segments as usual, has these 
very closely and firmly united. In the abdomen, the number of visible 
segments varies from nine to five, or even four in some instances. The 
legs, usually at least, are well developed, with a pair of claws at the tip 
and a pulvillus at the base of each claw. Between the claws there is 
often an membranous pad, similar to a pulvillus, or it may be a bristle. 
In either case, this centrally placed structure is called an empodium. 

On the surface of the body, bristles are often present which have 
definite positions and are of aid in identifying the species. 

Fly larvae are usually called maggots. Some have well developed 
heads while in others no structure of this nature can be recognized. 
True legs appear to be absent, though projections of the body which can 
be utilized in moving about are common and often bear circlets of hooks. 
These vary in their position in different species. The larvae breathe 
through spiracles, but the location of these differs greatly. In some they 
are found along the sides of the body as usual; in others there is a pair 
near each end of the body; in still others there is only one pair at the 
hinder end, and these may occur at the tip of a very extensible tube 
which, when fully stretched out, may be several inches long. Nourish- 
ment is sometimes obtained by osmosis directly through the body wall 
of the larva but it is generally taken into the mouth. The mouth parts 
in the least modified forms are of the chewing type but in most members 
of the order they are greatly modified. In some cases, a pair of claws or 
hooks appear to be the only structures, while in others a chitinous "rake" 
consisting of a cross-bar bearing a row of teeth and connected with a 
single rod running backward, serves to rasp and break open the vegetable 
cell walls and expose their fluid or semifluid contents of which the larva 
avails itself. 

Some flies construct regular cocoons but the pupa is usually either 
naked or located in a puparium which is the last larval skin. In this 
case, the larva, when ready to pupate, shrinks away from its skin and 
pupates within it, using this skin or puparium as a protection instead 
of making a cocoon. Escape from the puparium may be either through 
a T-shaped split on the back near the front end; a transverse split 
between the eighth and ninth abdominal segments in a few cases; or 
through a circular opening in the front end. 

The chief distinctive characters of the Diptera are: 

Insects which when adult have, with a jew wingless exceptions, only two 
wings, these attached to the mesothorax; the hind wings greatly modified, 
each consisting of a small knob attached to the metathorax by a stalk, these 
structures being called halteres; mouth parts for sucking, and sometimes 
jor piercing also. The larvce are called maggots and are without true 
legs. Metamorphosis co7nplete. 

This is one of the large orders of insects and members of the group 



304 



APPLIED ENTOMOLOGY 



are found in all parts of the world. They differ greatly in their habits, 
food, and general modes of life. Some are serious pests either of crops 
or of man, while others are among the most beneficial insects known, 
acting as parasites. A number of species function as carriers of disease- 
producing organisms and are of importance in that way. 

About fifty families of Diptera are recognized, many of them very 
large while others contain few species. 




Fig. 320. — Large Crane-fly (Tipulid) , head bent downward and almost wholly concealed; 
halter of right side showing plainly. Natural size. {Original.) 



Family Tipulidae (The Crane-flies). — This is a large and widely distributed 
family composed of Diptera having long and rather slender bodies and very long 
legs; in fact resembling enormous mosquitoes in appearance though a few are 
very small (Fig. 320). The antennae are generally thread-like and there is a broad 
V-shaped groove or suture on the top of the thorax. 

The larvse of crane-flies in most cases live in the ground and feed on the roots 
of grasses and grain and at times cause much injury in this way. Some exceptions 
live in decaying wood, on leaves, in water or elsewhere. There seem to be two 
generations each year, adults appearing in the spring and fall, and winter is 
passed as the partly-grown maggot. Injury is most often noticed on low or poorly 
drained land or where a field has been left in grass for a number of years. Control 
of these insects, when they are sufficiently injurious to make it pay, is by drain- 
ing, rotation of crops and plowing early in the fall, when the insects are in the 
pupa stage just below the surface of the ground, to crush them there. 



THE DIPTERA 



305 



Family Culicidae (The Mosquitoes). — These are small insects, famil- 
iar to everyone as they attack man and other animals, and in most 
species the females feed upon blood. A few species appear to consume 
plant juices. The mouth parts of the males are much reduced and the 
members of this sex rarely, if ever, feed. There are many kinds of 
mosquitoes but the larvae of all live in water and generally not in large 
ponds but in more or less stagnant water, and the most abundant species 
develop in temporary pools. 

The adults have scales fringing their wings and also along the veins. 
The antennae of the males are plumose (feather-like) and very noticeable. 
The winter is passed either as the 
egg, larva or adult, according to 
the species concerned. 

The eggs may be laid either 
singly, in small clusters, or in 
masses often called "rafts" on the 
surface of standing water or even 
on the ground, hatching in the 
latter case after rains or the melt- 
ing of the snow in spring. The 
number of eggs laid by one insect 
varies in different species but 
probably averages several hundred. 

The larvae or "wigglers" live 
in water and move with a motion 
which has given them their com- 
mon name. The head and thorax 
are large and distinct, while the 
abdomen is slender, and projecting 
from next to the last segment of 
this section of the body is a re- 
spiratory tube which is usually 

rather long and near the end of which the breathing organs open by 
a sort of spiracle. When air is desired, the larva floats to the surface 
and projects the tip of the respiratory tube just above the water level, 
to renew its supply (Fig. 321). 

The larvae have mouth parts of the chewing type, and some are plant 
feeders. Most of them, however, are predaceous, feeding on tiny water 
animals and even on other mosquito larvae, a pair of small brushes 
at the mouth being used to cause currents in the water and bring food 
within their reach. They molt four times and, after a varying length 
of time (a week or 10 days in many cases) in different species and at 
different seasons of the year, transform into pupae. These are quite 
different in appearance from the larvae, the head and thorax forming a 

20 




Fig. 321. — Breathing position of larva 
of Culex (below), and feeding and breath- 
ing position of Anopheles (above). Much 
enlarged. {Modified from U. S. D. A. Div. 
Ent. Bull. 25, n. s.) 



306 



APPLIED ENTOMOLOGY 



large, rounded mass, joined by a slender abdomen. Differing from 
most insect pupse, the pupal mosquito is active, moving through the 
water by a curious tumbling end over end. On the top of the thorax 
in this stage are two breathing tubes (Fig. 322), and when air is desired 
the tips of these are pushed above the surface of the water. The animal 
swims by making use of a pair of leaf-like appendages at the end of the 
abdomen. 

After a brief pupal stage, usually lasting only a few days, the animal 
comes to the surface of the water and a split of the pupal skin along the 
middle of the back of the thorax appears, through which the adult 
mosquito escapes, balancing itself on this skin until it is ready for flight. 





Fig. 322. — Pupa of Anopheles (left) and of Culex (right) showing po.sition when breath- 
ing. Difference of form, position in the water and in the breathing tubes are shown. 
Greatly enlarged. {Modified from U. S. D. A. Div. Ent. Bull. 25, n. s.) 



Of the many kinds of mosquitoes known, a small number are of 
particular importance aside from their habit of attacking man, being 
disease-carriers. 

The House Mosquito {Culex pipiens L.). — This is a very common 
species almost everywhere in the Northern United States east of the 
Mississippi River and north of North Carolina. It is probably a native 
of the Old World where it is also abundant. Though as far as known it 
is not a carrier of any human disease yet it is a most irritating pest, and 
its control is important on that account. 

Winter is passed as the adult (Fig. 323) in protected places and, in 
spring, egg clusters containing from 100 to about 300 eggs are laid on the 
surface of water. These eggs hatch in from 1 to 4 or 5 days and the 
larval stage usually continues for a week or two (Fig. 324). During this 
period, the larvse spend much of their time at the surface, the respiratory 
tube projecting slightly above the water-line and the body hanging 
downward. Pupation for a few days follows, after which the adult 
appears. There are a number of generations each season. The adult 



THE DIPT ERA 



307 



has unspotted wings and, when at rest, its body is parallel to the object on 
which it has alighted (Fig. 325). 

A number of other species not concerned in carrying disease are 
also liable to be pests. Near salt marshes of the eastern and southern 










Fig, 323. Fig. 324. 

Fig. 323. — ^Male House Mosquito (Culcx pipicns L.), greatly enlarged. Note the 
large feathery autennae of this sex. {From U. S. D. A. Div. Ent. Bull. 25, u. .s-.) 

Fig. 324. — Larva of House Mosquito, greatly enlarged. {After Howard, Dyar and 
Knab.) 




Fig. 325. — Alighting positions of Anopheles (left) and C'ulex (right) Mosquitoes. 
U. S. D. A. Div. E7it. Bull. 25, n. *•.) 



{From 



United States, the Salt Marsh Mosquito (Aedes sollicitans Walk.) is 
very troublesome, .and this species may fly quite a long distance inland. 
In the West, other species are abundant. 

The Malarial Mosquitoes {Anopheles quadrimaculatus Say and 
others). — The species of Anopheles are carriers of malaria. The adults 
(Fig. 326) are larger than those of the House Mosquito and their wings 



308 



APPLIED ENTOMOLOGY 



are marked with dark spots. In alighting on an object, the body is 
tipped at quite an angle to the object on which it rests (Fig. 325) and 
these two differences will at once serve to distinguish the malarial mosqui- 
toes from other species. Another distinction is in the length of the palpi 
of the female which in the House Mosquito are short, while in the Malarial 
Mosquito they are as long as the beak and therefore quite noticeable. 
The species of Anopheles named above is found from Canada to 
Mexico, east of the Rocky Mountains. 





Fig. 326. Fig. 327. 

Fig. 326. — Female Malarial Mosquito {Anopheles punctipennis Say) much enlarged. 
Antenna of male at right. (From U. S. D. A. Div. Ent. Bull. 25, n. s.) 

Fig. 327. — Larva of Malarial Mosquito, greatly enlarged. {After Howard, Dyar 
and Knab.) 



Winter is passed as the adult, and the eggs are laid singly on the 
surface of water and hatch 2 or 3 days later. The larvae (Fig. 327) 
resemble those of the House Mosquito but have a shorter respiratory 
tube and lie horizontally just below the surface instead of hanging head 
downward. (Fig. 321). The larval period is about 2 weeks, followed by 
a pupal stage lasting 2 or 3 days. Accordingly, a. new generation of 
these mosquitoes may appear about every 3 weeks. 

Most species of Anopheles attack man chiefly during the twilight 
and early morning hours. The various species of Culex seek their food 
at night though often beginning their work late in the afternoon. 



THE DIPT ERA 309 

Different species of Anopheles appear to be connected with different 
types of malaria. Anopheles quadrimaculatus has been proved to carry 
the organisms causing both the tertian and quartan forms while Anopheles 
crucians is a carrier of the organisms producing the sestivo-autumnal 
type of the disease, and, in other parts of the world, other species play 
similar roles in relation to these forms. 

The animals causing malaria are believed to be of three closely 
related kinds, belonging to the Protozoa. In its form when introduced 
into the blood of man, the animal is a rather long and slender spindle 
with pointed ends. It now assumes an amoeboid form and attacks a 
red blood corpuscle, working into it, feeding on its haemoglobin contents 
and producing black granules. It feeds on the hsemoglobin in the 
corpuscle until this has all been consumed and grows until it nearly fills 
the corpuscle. It now divides into many parts, each similar to the one 
which first entered the corpuscle, and these proceed to attack other 
corpuscles in a similar way. This breaking up of the animal into parts 
coincides with the ''chill" of the disease and the interval of time between 
successive chills determines which type of malaria is present, a period of 
2 days indicating the tertian type; 3 days the quartan type, while a 
varying period indicates the sestivo-autumnal type. As the parasites 
increase in abundance and consume more of the corpuscles, the patient 
becomes anaemic and weaker. 

Some of the products of division in the corpuscle, however, do not 
proceed to attack other corpuscles and increase in numbers but ai-e of 
two different kinds which al-e the sexual stages. When these are taken 
into the stomach of an Anopheles which attacks a person having malaria, 
the two kinds fuse and the resulting animal penetrates the cells of the 
stomach wall of the moscjuito and there remains, forming a cyst. Divi- 
sion of the animal here results finally in the production of cells like those 
which enter human blood, and these now escape into the body cavity of 
the mosquito and gradually gather in its salivary glands whence, they 
are expelled into the wounds caused by the feeding of the mosquito there- 
after. The time which must elapse after a mosquito has received the 
malarial parasites before it can transmit these to man varies, but is 
usually at least 10 or 12 days and may in sdme cases be more than this. 

The Yellow Fever Mosquito (Aedes cegypti L.). — This insect, for- 
merly known as Stegomyia fasciata, is the carrier of Yellow Fever. It 
occurs in the tropics throughout both hemispheres and, during warm 
weather, may extend to the temperate regions. but can survive there 
only while the temperature is fairly high. 

The adult (Fig. 328) is a small mosquito with silvery hues along the 
back of the thorax and its legs are banded with white. It flies in the 
daytime and occurs mainly in towns and cities, being only rarelj^ found 
in the country. Its eggs are laid singly or in small clusters on, or close 



310 



APPLIED ENTOMOLOGY 



to, water in houses or near by, it having apparently become a "wholly 
domesticated" species. The eggs hatch in from 10 hr. to about 3 days, 
and the larvae hang downward from the surface. After a week or 10 
days in this stage, they pupate for 2 or 3 days before the emergence of the 
adult. Feeding by the adult appears to be mainly during the warmer 
hours of sunny days though extending somewhat into the evening. 

Repeated investigations show that the unknown germ or organism 
producing Yellow Fever is conveyed to man only by the attacks of this 
insect. Apparently about 12 days is required after feeding on a Yellow 
Fever patient before the mosquito is able to transmit the organism caus- 
ing the disease, but from that time on it can do 
this for well over a month. 

Dengue and Filariasis, two other important 
diseases of man in tropical and subtropical 
regions, are also known to be carried by 
mosquitoes. 

Control of Mosquitoes. — There are many 
ways by which mosquitoes can be more or less 
effectively controlled. The thorough screening 
of houses to keep them out is a desirable prac- 
tice and is also of value as a protection against 
house-flies. Nettings over beds for the same 
purpose are often used where entire houses are 
unscreened. Out-of-doors, veils covering the 
head, and gloves for the hands are often necessary 
in places where these insects are extremely 
abundant. Protective materials rubbed on ex- 
posed parts of the body are also often used and 
various substances have proved of value for this purpose. Among these 
arc spirits of camphor, oil of pennyroyal and oil of citronella which seem 
to be the favorite substances used in this way. Smudges will keep away 
mosquitoes where the smoke is, and burning insect powder in a room 
stupifies the insects so that they fall to the floor and can be swept up. 
Other materials for use in a similar way are also available. 

Destruction of the larvae, pupae and eggs is the most direct way in 
which to control mosquitoes in large numbers, and many methods for 
accomplishing this have been tried. As mosquitoes develop only in 
water, the removal of the places where they can breed, such as the drain- 
age of marsh land, filling up small pools, hollows in trees containing 
standing water, and all such situations will accomplish a great deal. 
The drainage of the salt marshes of the New Jersey coast and elsewhere 
has resulted in a marked relief from the attacks of mosquitoes in those 
localities. Where the water can not be drained off, covering it with a 
film of kerosene will suffice to destroy the eggs on the surface, larvae and 




Fig. 328.— Adult Yellow 
Fever Mosquito (A cdes 
oegypti'L.), considerably en- 
larged. Note black and 
white banding of the legs. 
(After U. S. D. A. Farm. 
Bull. 547.) 



THE DIPT ERA 811 

pupae at or coming to the surface for air, and any adults which may ahght 
on the water to lay their eggs. Rain water bai'rels and cisterns for storing 
water for use can be screened, and ponds where the use of oil is undesirable 
may be stocked with small fish (sun-fish or top minnows) which feed 
voraciously on these insects. Recent experiments indicate that where 
the water must be used for drinking purposes, making the use of oil 
objectionable, sprinkling powdered formalin on its surface will kill 
mosquito larvae but not fish present, without making the water impossible 
to drink! 

The catch-basins of sewer openings are usually favorite breeding places 
for mosquitoes and these must be given attention, along with cess-pools 
and any tin cans or other receptacles containing rain water which can be 
found. 

Oil used should be sprayed on the water, working preferably along its 
windward side and using about 1 fi. oz. to every 15 sq. ft. of surface. 
The oil will spread if simply poured onto the water, but rather rilore of it 
will be required by that method. It is important to be sure that little 
detached pools along the shore receive their film of oil also. This treat- 
ment should be repeated every 10 to 15 days unless heavy rains carry off 
the oil soon after a treatment, in which case the oil should be renewed 
sooner. Sawdust soaked in kerosene has been found to give up the oil 
slowly and thereby preserve the film on the surface longer, when this 
material is scattered along the edge of the water. 

Famihj Itonididae (The Gall Midges). — These tiny flies are very 
numerous. Most of them produce galls on plants, living in these galls, 
but some suck plant juices without producing galls, and a few live in 
decaying wood or fungi, or even feed on Aphids. The adults have long 
antennae with, in the majority of the species, a whorl of hairs on each 
segment. All parts of the plant are attacked by one species or another, 
and the galls produced are typical for the species in each case. 

The gall appears to be the result of the irritation caused by the larva 
feeding, and to some extent its size is dependent upon the number of 
larvae present. Winter is frequently spent as the larva inside the gall 
and, in many cases, there is but one generation each year though, on the 
other hand, some species have several generations. 

The larvae are small, often brightly colored maggots. The method of 
pupation varies in different species, some forming true cocoons while 
others have a puparium and others are without any covering. 

Among the species not producing galls is the Clover-flower Midge (Dasyneura 
leguniinicola Lint.) which lays its eggs in the flower heads of mammoth, red, 
crimson and white clover and is probably present everywhere in America where 
these clovers occur. There are two generations each year. The larvse feed on 
the flowers and prevent their forming seed. As the insects do not affect other 
parts of the plant, they are not of serious importance except where seed is grown, 



312 



APPLIED ENTOMOLOGY 



but in those localities they are very injurious pests. The usual methods of control 
are to pasture the fields before starting a seed crop, to destroy all the midges 
present in the heads then available : by early cutting, to dry up the heads before 
the maggots in them have finished feeding, which in the northern districts would 
mean cutting early in June. Sometimes, cutting the clover back between the 
fifteenth and twenty-fifth of May will prove advantageous as the new blossoms 
will not develop until after the adults of the first generation are gone, and will 
have progressed beyond danger of injury by the time the adults of the second 
generation appear. Clover so cut can be fed green to stock. 

The Hessian Fly {Phytophaga destructor Say). — This insect, which 
Hke the last is one of the non-gall-making Itonididae, is a native of Europe 
and was first noticed in this country about 1779 on Long Island, N. Y. 
Since that time, it has spread over a large part of the United States and 

Canada and is now one of the most 
injurious insect pests in the country, 
often destroying wheat valued at 
millions of dollars. It feeds on wheat, 
barley, rye, and several other species 
of grasses. 

Its life history differs somewhat in 
different places, apparently being 
modified by the different methods of 
wheat growing. Where wheat is 
planted in the fall, the eggs are laid 
on the leaves of the plants soon after 
they come up, the time varying with 
the latitude from late August and 
September in Michigan, to the last of 
November or early December in 
Georgia. The eggs are placed in ir- 
regular rows of about half a dozen, 
generally on the upper surface of the leaf, and each fly lays 100 to 150 in 
all. They hatch after a few days, and the tiny pinkish or reddish maggots 
work their way down between the leaf and the stem to a point just above 
the joint (Fig. 329). Here they remain, sucking the sap until the 
approach of cold weather, turning more nearly white in color. Their 
presence at this time is at first indicated by the dark color of the leaves, 
missing stems which would otherwise begin to show, and later, the yellow- 
ing and death of the plants. After feeding about a month, the larva 
pupates within its larval skin which therefore becomes a puparium and so 
greatly resembles a flax-seed that in this condition the insect is generally 
spoken of as being in the "flax-seed" stage. In this condition, it spends 
the winter and the adult flies (Fig. 329) emerge in the spring; early in the 
South; later in the North. These now lay their eggs on the wheat and, 




Fig. 329. — Hessiau Fly (Phytophaga 
destructor Say): a, adult fly; b, wheat 
plant affected; c, maggot. Hair lines 
show true length of a and c. {From 
Berlese.) 



THE DIPT ERA 313 

as by this time the plants may be a number of inches high, the eggs 
can be laid at different heights on the plant, and the larvae will pass down 
to the joints immediately below the leaves on which the different eggs 
are laid. Feeding at these joints continues during the spring and the 
flax-seed stage is reached at or before harvesting time. Some of the 
flax-seeds will be in the straw cut and harvested while many more will 
remain in the stubble and the flies emerge from the flax-seeds during the 
early fall as already indicated, ready to attack the fall-planted wheat as 
soon as it comes up. 

In regions where the wheat is planted in the spring, the insect winters 
in the flax-seed stage in stubble and volunteer wheat, and the adults 
appear in May. The second generation quickly follows the first, particu- 
larly in wet seasons, and there seems to be no period of delay such as 
occurs during midsummer in the fall-wheat regions. 

Control. — The Hessian Fly has numerous parasites which are undoubt- 
edly of much value, as where great loss occurs these insects are few in 
number. It is so often the case, though, that the fly is abundant, that 
parasites can not be relied upon and other measures, largely preventive 
in their nature, must be taken. 

It is evident that, if fall planting can be delayed until the adults 
which appear at that time are gone, the crop will be protected from 
attack. To carry out this plan, however, latitude, elevation and humid- 
ity perhaps, as well, must be taken into consideration. Investigations 
along this line, though far from complete, now indicate that it is generally 
safe to plant wheat in northern Michigan after the first of September: 
in southern Michigan and northern Ohio, about the twentieth of that 
month: in southern Ohio, after October 7: in Kentucky, after October 
15 : and in Georgia, from the last week in October to the middle of Novem- 
ber. Thus in general, the farther south, the later the planting date 
should be, though very high land in any region can probably be planted 
earlier than low land if the area and elevation are sufficient to give it the 
more northern conditions. 

The rotation of crops is also of advantage, driving the flies elsewhere 
to lay their eggs and making them more liable to destruction while 
en route. 

Many of the flax-seeds are left in the stubble at harvesting and 
any method of destroying these is beneficial. Where the grain is cut 
rather high and a mowing machine is then run over the field, cutting 
the stubble as close as possible, burning this cut stubble after a few days' 
drying is effective. Unfortunately, however, the general custom of 
planting grass and clover in such fields, to come up as the grain progresses 
toward harvesting, too often makes this control impracticable. 

Volunteer wheat as it is called, coming from grain scattered through 
and around the wheat fields by accident, starts early and provides plants 



314 APPLIED ENTOMOLOGY 

for the Hessian Fly to lay its eggs on before the main planting is avail- 
able. This will produce an abundance of the insects to attack the crop 
the following spring. All such plants should be destroyed before the 
maggots in them have reached the flax-seed stage. 

The use of good seed, planted in soil that has been thoroughly culti- 
vated to break up all the lumps of dirt and thus provide a compact, 
fine soil, is very helpful, and the addition of plenty of fertilizer is also of 
importance. 

One writer has summarized control methods for the Hessian Fly 
as follows: "Sow the best of seed in thoroughly prepared, fertile soil 
after the major portion of the fall brood has . . . passed out of existence, 
and, if possible, sow on ground not devoted to wheat the preceding year. 
In the spring-wheat section late seeding will not apply. It seems likely, 
on the contrary, that the earlier it is sown in spring the less it will suffer 
from the Hessian Fly," (Webster). 

Another Itonidid attacking wheat, and also barley, rye and oats occasionally 
is the Wheat Midge {Contarinia tritici Kirby), a native of Europe, first noticed 
near Quebec about 1819, and which has now spread over the wheat-growing 
regions of the East, and through the Mississippi Valley. The adults are very 
small, yellow or orange colored, and appear in June. The}^ lay their eggs in the 
chaff covering the growing kernels of grain, and the reddish maggots suck the 
juice from the kernels causing them to shrivel, blighting the heads. When full- 
grown, the maggots pupate in the ground, usually passing the winter in this stage. 
There is generally only one generation each year. 

For many years, this was a very serious enemy of wheat, the loss in New York 
being estimated at S15,000,000 in 1854, but since about 1860 it has been less 
destructive and only local in its attacks. Plowing infested land deeply in the fall 
so that the insects wintering there will be buried too deeply for them to escape 
the following spring: burning the chaff and screenings after threshing the grain 
from infested fields, and rotation of crops are the control methods used for 
this pest. 

Family Tabanidse (The Horse Flies or Gad Flies). — These pests of 
cattle, horses, and occasionally of man also (Figs. 330 and 331) are in many 
cases quite large insects, with bodies an inch long though most of them 
average a third to half an inch in length. The head of the adult is large 
and fits onto the thorax somewhat like a cap. Only the females feed 
on blood, the males lacking some of the mouth parts necessary with 
which to pierce the skin. They therefore feed on such plant juices as 
they may be able to obtain, honey dew and other similar materials. 

The eggs are laid in masses on plants over water or marshes, and the 
larvae live in water, damp places, or in the earth when it is soft, and are 
carnivorous, feeding on snails, small insect larvae, etc. 

The family is a large one, both in this country and elsewhere. The 
larger species, (one has a black body and smoky wings) , are often noticed 



THE DIPTERA 



315 



around domestic animals because of their size. Many of the smaller kinds 
have wings banded with dark. Some of these are called" Green-heads" 
because of the bright green color of their eyes (Fig. 331). Their attacks 
irritate and disturb the animals and, in the case of milch cattle, this 
may reduce the amount of milk produced. 

As these insects attack domestic animals only for their blood, any 
repellent measures which prevent this are sufficient. Fly-nets covering 
the greater part of the animals are sometimes used for this purpose: and 
smearing the ears and legs with substances having an odor objectionable 
to the flies is also practiced. One of several materials often applied is 
fish oil, either alone or mixed with tar. The following mixture has proved 





Fig. 330. Fig. 331. 

Fig. 330. — Large Horse Fly {Tahanus stygius Say), slightly reduced. {Original.) 
Fig. 331. — Small Horse Fly {Chrysops vittatus Wied.), over twice natural size. 
{Original.) 

effective against those Tabanids which preferably attack the ears and the 
region around the eyes of the animals: pine tar, 1 gal.; fish oil or crude 
carbolic acid, 1 qt.; powdered sulfur, 2 lb. These materials are thor- 
oughly mixed and rubbed on the parts most liable to be attacked. As so 
many Tabanids pass their early stages in stagnant water, the treatment 
of such breeding places with kerosene will destroy the larvae as they hatch 
and enter the pools. 

Family Simulidae (The Black Flies or Buffalo Gnats). — The small flies which 
compose this family feed upon the blood of man and other animals, attacking 
them at all exposed places. As in the TabanidsD, only the females are concerned 
and these are active only during the daytime. The eggs are laid in such places 
that the larva? can enter water, and in most cases, swiftly running streams where 
they feed on small animals. They usually anchor themselves to some object in 
the water and have a pair of fan-shaped structures at the mouth which are used 
to produce currents toward the mouth. In the South, all domestic animals suffer 
severely from the attacks of these insects, and many are even killed by them. 
There are usually two or three generations each year, particularly in the South. 
The best control methods known are the use of repellent materials on the animals, 
such as fish oil three parts, kerosene one part, applied about twice a day. Ani- 
mals kept in dark stables are not attacked while there. 



316 



APPLIED ENTOMOLOGY 



Family Asilidae (The Robber Flies). — These insects as adults prey 
upon other insects, attacking any species they are able to overcome (Fig. 
332), but using little discrimination as to the importance to man of their 
captures. They can hardly be regarded as more than accidentally 
beneficial to man. Some species (Fig. 333) so closely resemble bumble- 
bees that a careful examination of the number of wings present is necessary 
to determine what the insect is. The larvae are found chiefly under bark, 
in decaying wood or in the ground where decaying vegetable matter occurs, 
and feed upon insect larvae present in such places. 




Fig. 332. Fig. 333. 

Fig. 332. — Robber Fly {Scleropogon picticornis Loew), about twice natural size. 
{From U. S. D. A. Bull. 124.) 

Fig. 333. — Bee-like Robber F\y {Dasyllis grossa Fah.), slightly reduced. (Original.) 

This family is one of the largest in the order and its members average 
large, ranging from a length of about a fifth of an inch to nearly two inches: 

Family Syrphidae (The Syrphus Flies). — This is one of the largest 
families of Diptera. The adults range from quite small to rather large 
insects which visit flowers, feeding on the pollen and nectar, and are most 
noticeably abundant in bright, sunny weather. They are usually rather 
brightly colored. 

The larvae of these insects vary greatly in their appearance, five types 
of them having been recognized. Some are rather flattened, elongate, 
often green with white spots, and are found with clusters of plant lice on 
which they feed. Others have nearly cyhndrical bodies and bore into 
the bulbs of various plants. Others live and feed in filth and have short 
extensible tubes for respiration. Another class which also inhabits filth 
has extensible respiratory tubes which, when extended to their limit, may 
be several times the length of the body. Still another group are short, 
broadly rounded, flattened beneath and high above, somewhat hemispher- 



THE DIPTERA 



317 




Fig. 334. — Adult female Bot Fly (Gastrophilus fianalis L.), nearly twice natural size. 

(Fro7n U. S. D. A. Bull. 597.) 




Fig. SSS.-^-Nearly full-grown larvae (bots) of a Horse Bot Fly attached to the inside wall 
of the stomach. {From U. S. D. A. Bull. 597.) 



318 



APPLIED ENTOMOLOGY 



ical in form. These are usually found under logs and in ants' nests and 
may easily be mistaken for rather peculiar snails. 

Though the adults consume pollen, their visits to flowers are valuable 
to man for the cross-pollination and the resulting "setting" of seed. 
The insect-eating larvae often destroy enormous numbers of insect 
pests, and the filth-inhabiting forms are at least cleaning up decay- 
ing matter, which is generally considered desirable. On the other hand, 
some are injurious by boring into the bulbs of cultivated plants, and sev- 
eral species cause myiasis in man and some of the domestic animals, these 
insects in one way or another entering the body and passing through their 
larval development there. 

Family CEstridae (The Bot Flies). — The bot flies in their early stages 
are parasites on mammals. The adults are of medium to large size, 
with rather stout, thick-set bodies and frequently with reduced mouth- 
parts, not feeding in this stage (Fig. 334). Though the group is not a 
large one, its members are included among the more important pests of 
domestic as well as of other animals. The parasitic part of the life of 
these insects is in some species spent in the stomach (Fig. 335) or intes- 
tines, in others in the pharynx or nasal cavities and frontal sinus, while 
others live under the skin. 



''•^'L:.^- 





M' 's 

^%^ 




'm 



Fig. 337. 
Real length shown by hair 



Fig. 33G. 

Fig. 336. — Ox Warble Fly (Hypoderma Unrata VilL). 
line. {From U. S. D. A. Div. Ent. Circ. 25.) 

Fig. 337. — Full-grown Warble (larva), dorsal view (left) and side view (right) 
Real length shown by hair line. (From U. S. D. A. Div. Ent. Circ. 25.) 



The Ox Warbles (Hypoderma lineatwm Vill. and Hypoderma bovis De 
G.).^These two insects, both natives of Europe, are present in this 
ocuntry, the former widely distributed, the latter most abundant in 
Canada and a few of the Northern States. The adult fly (Fig. 336) is 
about half an inch long. The eggs of both species are laid on the hairs of 



THE DIPT ERA 319 

cattle on almost any part of the body during the late spring or summer 
months, and the larvae bore through the skin into the connective tissue 
and then wander through the body in the connective tissues until late fall 
or winter when they locate along the back, a few inches from the back- 
bone. Here each makes a hole through the skin through which to escape 
but remains inside, feeding on the pus and bloody matter produced by its 
presence there, and the swelling caused by the insect is called a "warble." 
Finally the maggot, now nearly an inch long (Fig. 337; and grayish-white 
in color, works its way out through the hole and drops to the ground which 
it enters for an inch or two, and forms a pupa within a brown puparium 
from which the adult fly appears from 3 to 6 weeks later, the larval period 
within the cattle being 9 or 10 months. 

The presence of the maggots of the ox warbles in the cattle is shown 
by a loss of flesh, reduction of the milk in the case of milch cattle, and by 
the presence, during late fall and winter, of the sores on the back. 

Control. — The chief control method in general use is squeezing out the 
larvae in the back whenever they are observed there. With a little 
practice, pressing with the thumbs on the skin at the sides of the opening 
will result in the expulsion of the maggots. During the egg-laying season, 
cattle in the field may be protected to a considerable extent by the appli- 
cation of repellents such as are used to keep off Tabanids. 

Various other bot flies attack different animals. Among them are 
the Horse Bot Flies (Gastrophilus of several species), the larvse of which 
live in the stomach of the horse during the fall, winter and spring and the 
Sheep Bot Fly {(Estrus ovis L.) which in the larval stage inhabits the 
nasal cavities and frontal sinuses of sheep during the same period. 

Family Trypetidae (The Fruit Flies). — Some of these small flies attack 
various fruits in which their maggots tunnel, ruining the fruits. Others 
mine the leaves of plants, occur in blossoms or form galls in the stems or 
roots of plants. Those which live in fruit are of economic importance. 
Most of the flies belonging here have dark bands, or dark markings 
enclosing transparent spots on their wings. Two species attack cherries; 
one feeds in currants and gooseberries; one in the apple, thorn, blueberry 
and huckleberry, and other species injure citrus fruits. 

The Apple Maggot or Raikoad Worm {Rhagoletis pomonella Walsli). — This 
insect is apparently a native of this country and its original food seems to have 
been the berries of the thorn and possibly the blueberry. It has been found in 
various parts of Canada and the eastern United States as far south as North 
Carolina and west to Minnesota, South Dakota and Colorado, but is most serious 
in the northern and eastern portion of this territory. 

The adult (Fig. 338) is about a fifth of an inch long and has a wing spread of 
about half an inch. Its body is black with light marks on the upper side of the 
abdomen, and the wings have heavy dark bands. The flies first appear in the 
orchards early in July in New England (somewhat earlier farther south) and 



320 



APPLIED ENTOMOLOGY 



attack the early varieties of apples. Later appearing flies may sometimes be 
found until into September, and these select fall and winter fruit for egg laying. 
Some varieties of apples are much more subject to the attacks of this insect 
than are others. 

Egg laying begins about 20 days after the fly emerges and probably continues 
for 2 or 3 weeks, the total number of eggs laid being several hundred. These 
are inserted singly under the skin of the apple and preferably where the surface 
is not exposed to sunHght. They hatch in 4 or 5 days and the little whitish 
maggots tunnel through the pulp of the fruit in all directions. At first, the 
rapid growth of the fruit may fill up these tunnels, but after a time the walls 
around the tunnels instead of filling in, turn brown and the fruit softens, decay 
may follow, and the entire apple is spoiled for sale. The maggot (Fig. 339) has 
no real jaws with which to tunnel but has a pair of small hooks at the mouth 
opening with which the pulp is rasped and torn, freeing the juice upon which 
the insect feeds. 





Fig. 338. Fig. 339. 

Fig. 338. — Adult Fly of the Apple Maggot {Rhagoletis pomonella Walsh), slightly 
over three times natural size. (Reduced from Nova Scotia Dept. Agr. Bull. 9.) 

Fig. 339. — Puparium (left) and full-grown maggot (right) of the Apple Maggot. 
About three times natural size. (Modified from Nova Scotia Dept. Agr. Bull. 9.) 



The length of the larval stage depends upon the temperature and upon the 
ripeness of the fruit. In warm weather and with rather soft pulp, about 2 to 4 
weeks is usually the time necessary, but with colder weather and in late-maturing 
varieties, growth toward maturity is delayed and some maggots may possibly 
even winter in this stage in extreme cases. When the larva has completed its 
feeding, however, it leaves the fruit (usually as this becomes ripe) and enters the 
ground where it burrows below the surface' often some distance, and pupates in 
a puparium (Fig. 339) remaining here until the following summer when the flies 
emerge. Where infested fruit is gathered and stored before the maggots leave it, 
the puparia may be found on the bottom of the barrels or bins where the fruit is 
kept. A few of the earlier pupating maggots appear to transform to flies the 
same season, giving a second generation, but so few do this that it is of little or no 
economic importance. On the other hand, a few seem to require 2 years for 
the completion of their life history. 

The amount of injury caused where this insect is abundant is often very great, 
particularly with early apples, a large percentage of which may prove entirely 
worthless. Among the varieties which suffer severely are the Early Harvest, 
Gravenstein, Porter, Red Astrachan, and Wealthy, sweet and sub-acid summei: 



THE DIPTERA 321 

and fall varieties being in general the greatest sufferers though winter varieties, 
as the Northern Spy and others, often do not escape. 

The adult flies feed freely and also seem to require water during their life, 
specimens supplied with food but no water dying within a few days. They do 
not appear to fly freely for long distances at least, and orchards in which they are 
abundant and others where they are rather few in number may occur not very 
far from each other. 

Control. — Infested fruit falls to the ground early, and the maggots in it rarely 
leave it for the ground to pupate until about a week later. Gathering and 
destroying this fallen fruit promptly should, therefore, be of much assis- 
tance in controUing the insect but the amount of labor involved in carrying 
out this plan makes it impracticable in many cases. Cultivation of the ground 
under the trees has proved ineffective and allowing poultry and hogs to run in the 
orchards has not resulted in much improvement. 

It has been found that where orchards are carefully sprayed just about the 
time the flies appear, using slightly less arsenate of lead than the standard formula 
and repeating this treatment 2 weeks later, excellent results are obtained. The 
addition of molasses has sometimes been advised, but comparative tests thus far 
made indicate little advantage from this considering the extra expense and trouble. 
To know just when to apply the first spray is a difficulty with this treatment, 
however, and it has been suggested that owners of infested orchards can place 
infested apples in a box containing several inches of earth and leave it out during 
the winter. In the spring, cheese-cloth can be placed over the top and the spray 
should be applied as soon as the first flies are seen on the under side of the cloth. 

Family Muscidae (The Muscid Flies). — This large family contains 
many species which are important to man though none appear to be crop 
feeders. The adults range from small to medium size and are very 
abundant in most cases. 

The House-fly (Musca domestica L.). — This insect, always a house- 
hold pest, has during the last 25 years assumed a greater importance 
to most people because of the discovery that it is a carrier of a number of 
serious human disease-producing agents, among these being the germs 
of typhoid fever, cholera, dysentery, etc. 

The adult flies (Fig. 340) hardly need any description. They are 
rather small, with reddish-brown eyes, transparent wings and blackish 
bodies. Their mouth parts are for sucking and a "biting" fly found in a 
house at any time is of some other species. 

Winter is at least usually spent as the pupa or perhaps in some cases 
as the larva. As the weather becomes warm in the spring, the flies 
emerge, and, in temperate regions, begin breeding early in June, though 
it is probable that in warmer climates this may continue throughout the 
year. Most of the flies breed in manure piles, particularly those exposed 
to light, but almost any decaying animal or vegetable matter may be 
selected for the purpose. The eggs (Fig. 341) are laid in clusters, about 
125 at a time and about 500 to 600 in all. They hatch in from 8 to 12 

21 



322 



APPLIED ENTOMOLOGY 



hr. during warm weather but may take 2 or 3 days if the temperature 
is low. The larvae (Fig. 342) feed on the manure or other material in 
which they are located, for a varying number of days but probably 
averaging about 5 days. Pupation for about the same length of time 
follows, but many of the maggots may leave the place where they feed 
and travel a short distance away to pupate. Thus, pupae may be found 
in the ground around a manure pile within a foot or two. Pupation is 
within a puparium, the fly pushing off the front end by means of its 





^1 


/ 




^ 


f^^^^ 




yjt 


\ 



Fig. 340. 



-House Fly {Muaca domestica L.), rather more than twice natural size. 
duced from Hewitt: The House Fly.) 



Re- 





FiG. 341. Fk;. 312. 

Fig. 341. — Eggs of the House Fly, much enlarged. {Oritjinal.) 
Fig. 342. — Full-grown maggots of the House Fly, much enlarged. 



{Original.) 



ptilinum. After the emergence of the adult fly, a period of about 14 
days elapses before egg laying begins so that the time from one of these 
periods to the next during warm weather is about 24 days. From 7 
to 10 generations are liable to be produced, therefore, in a long season in 
the North or under ordinary conditions in the South, and it has been 
calculated that the descendants of a single fly which deposits its eggs 
the middle of April would number 5,598,720,000,000, by the middle of 
September, if all the eggs hatched and lived to adults which reproduced 
in their turn. Fortunately, this is not actually the case, eggs failing to 
hatch and many larvae never reaching maturity. 

House-flies as disease carriers are of extreme importance. Crawling 
over and feeding upon filth of any kind, their legs and bodies are liable 
to gather the germs of various diseases, which may also be taken into the 
flies with their food. Later, visits to houses and human food over which 



THE DIPTERA 323 

the jflies crawl lead to leaving some of the germs there, and the well- 
known habit they have of disgorging some of the food already eaten and of 
expelling feces, both of which may contain the germs swallowed, is pretty 
certain to infect the human food over which they crawl. 

Doubtless many of the microorganisms thus placed on food are 
entirely harmless to man but among these are also liable to be those 
which cause diseases. Milk exposed to the visits of flies may become 
infected in a similar way. 

Among the disease germs often transmitted thus are the typhoid 
fevers, anthrax, tuberculosis, cholera and yaws, while others are suspected 
of being carried in this way also. The habit flies have of visiting spit- 
toons; of alighting on sores on persons and, in fact, of crawling over 
everything where disease germs are liable to occur, makes them par- 
ticularly dangerous to man. It should be noted, however, that there 
seems to be no development of any of these diseases while on or in the 
flies themselves, the insects acting as passive carriers only, of the germs. 
The relation of the insect to the disease, therefore, is a totally different 
one from that of mosquitoes and the diseases in which they are concerned, 
where the disease-producing organism actually passes through a part of 
its life cycle in the insect. 

Control. — As over 90 per cent of the house-flies breed in manure, 
treatment of this to destroy the larvae and pupae there becomes an 
important line of attack. But, as in most cases this manure is used as 
fertilizer, the treatment should be, if possible, something which will not 
affect the value of this material for use. Most of the larvae live near 
the surface of the manure piles, and it has been found that treatments 
with materials which will penetrate six or eight inches into the piles will 
reach most or all of the insects. Three-quarters of a pound of common 
borax dissolved in 3 gal. of water and poured over the pile will be suffi- 
cient to properly treat 10 sq. ft. of surface of the pile to the depth of a 
foot, so that applying this amount of fluid to 15 sq. ft. should reach ah, 
or nearly all, of the larvae and pupae in this space. It should also be 
applied to the ground around the pile for a foot or two as many of the 
larvae crawl outside the pile to pupate. 

Too much borax in the manure injures it as a fertilizer, and, in many 
cases, it is better to use Hellebore instead. Half a pound of this in 10 
gal. of water is enough for 10 cu. ft. or to cover 15 sq. ft. to a sufficient 
depth to reach the insects. This treatment is somewhat more expensive 
than the other but the increased value of the manure is likely to more than 
make up the difference. 

Open latrines and any places in which house-flies are breeding should 
be treated to destroy the larvae and pupae present or covered in such a 
way as to prevent the flies from reaching them. Chloride of lime and 
iron sulfate have been used with considerable success to kill fly larvae 



324 



APPLIED ENTOMOLOGY 



and pupae or drive away the adults, particularly when sprinkled around 
in stables. Hauling the manure directly to the fields and spreading it 
there, when practicable, preserves more of its value than letting it stand 
in piles where leaching and other processes going on reduce this. The 
destruction of garbage and of the organic matter at public "dumps," 
in which flies breed, is also important. Screening houses, food and gar- 
bage pails or cans and trapping the adult flies either by poisoned or sticky 
fly papers or by the use of fly traps are all methods for reducing the fly 
pest which, when these insects are abundant, should be made use of. 

Almost any fly having habits similar to those of the house-fly may be- 
come a disease carrier in a similar way, and the above methods are of 
value against them all. 

Some of the flies in this family lay their eggs on meat, either decaying 
or fresh, which is then spoken of as "blown." The flies which do this 
are usually the ones commonly called "blue-bottle" and "green-bottle" 
flies. 




Fig. 343.- 



-Screw-worm Fly {Chrysomyia macellaria Fab.), greatly enlarged. 
U. S. D. A. Farm. Bull. 857.) 



(From. 



The Screw -worm Fly {Chrysomyia macellaria Fab.). — This pest occurs in 
South America and northward into Canada. It is a serious pest to live stock and 
other animals, chiefly in the Southwestern States, though occasionally it becomes 
important farther north and east. 

The adult fly (Fig. 343) is of a dark bluish-green color and has three black 
stripes along its back. It is considerably larger than the house-fly. Its eggs 
are laid in any decaying animal matter and also in wounds such as are caused 
by barbed wire, hooking, etc., in living animals. The larvse (Fig. 344) hatch in 
from a few hours to a day or two and burrow into the tissues, if the eggs were laid 



THE DIPTERA 



325 



on living animals, producing an irritating substance. The action of this and the 
feeding on the tissues cause the animal to become thin, lose its appetite and 
frequently death follows, for fresh eggs are repeatedly laid in the same wounds 
by the adults. The larva? mature in 4 or 5 days in living animals and more 
slowly in dead ones, and, on becoming full-grown, drop to the ground which 
they burrow into a few inches to pupate. The pupal stage lasts from 3 days to 
2 weeks and, at the end of this time, the adult flies emerge, completing the life 
cycle in from 1 to 4 weeks according to the conditions of the weather. 




Fig. 344. — Full-grown Screw-worm Maggot, greatly enlarged. {From U. S. D. A. Farm. 

Bull. 857.) 

Control. — Most of the breeding of these insects is in dead animals and there- 
fore all carcasses should be promptly buried or burned. To protect living live 
stock, efforts to prevent their injury must be made and all cases of injury cared 
for as soon as possible. This may be done by pouring a little chloroform into the 
wound. It is then generally advisable to remove the maggots and clean the 
wound with water containing 5 per cent of carbolic acid. Pine tar over the out- 
side at the wound will act as a repellent to the flies. In serious cases, the services 
of a veterinarian will be needed. Tick wounds are often the starting points for 
screw-worm injuries, and ticks should, therefore, be controlled as far as possible. 

The Tsetse Flies (Glossina of several species). — These Muscid flies 
are the conveyers to man of the dreaded disease known as "sleeping 
sickness. " The insects occur only in parts of Africa where they are 
found along wooded streams and where large game animals are present. 
The mouth parts of these flies include piercing structures and the insects 
normally attack the wild game, but man is also liable to their visits. 
The disease is caused by a Protozoan animal (Trypanosoma gambiense) 
obtained by the flies while feeding on infected animals, and the trypano- 
somes may be directly conveyed into another animal during the next 
day or two, after which the fly becomes innocuous for about 4 weeks: 
by this time, those of the parasites which entered the stomach of the fly 
have gone through a development in the body of the insect and have 
gathered in the salivary glands. The fly is now dangerous for about 3 
months. In man, the disease appears as an irregular fever, and an en- 
largement of the glands followed after a time by nervousness and sleep, 
the patient becoming comatose and finally dying. The earlier stage of 
the disease may last for several years but the last usually continues only 
from 4 to 8 months. 



326 



APPLIED ENTOMOLOGY 



Thus far no cure for the disease has been discovered but protection 
while in Tsetse districts can be obtained by screens, veils, gloves, etc., 
and by keeping away from the localities in these districts where the flies 
occur. Its importance is indicated by the estimate that in 10 years 
between four and five hundred thousand natives died from this disease. 
Another species of trypanosome carried by Glossina flies causes the 
disease of domestic animals, particularly horses and dogs, known as 
Nagana. This is almost always fatal to these animals. 

Family Sarcophagidae (The Flesh Fhes, Fig. 345). — This is a large 
family of flies, some of which lay their eggs on dead animals. Others 

breed in manure, decaying matter 
and similar materials, and because 
of these habits, there is always the 
possibility of their becoming car- 
riers of disease-producing germs, 
though as they seldom visit human 







/ 


l8i 


1 


^ 


i J. m 

n \ ^ 


i 


'\ t 




Fig. 345. Fig. 346. 

Fig. 345. — Adult Sarcophagid Fly (Sai-cophaga sp.), much enlarged. {From U. S. 
D. A. Farm. Bull. 857.) 

Fig. 346. — Adult Tachinid Fly {Tachina mella Walk.), over three times natural size. 
{From Brition, Tenth Rept. Ent. Conn. Agr. Exp. Sta. 1910.) 

food in houses, the chance that this may result in disease is much less 
likely than in the case of the house-flies. 

Family Tachinidae (The Tachina Flies). — This family has by some 
students of the subject been regarded as the most useful family of insects 
from an economic standpoint, its larvae being parasitic on other insects 
and being very abundant. This estimate of their importance is probably 
too high but the group is certainly very valuable in the control of injurious 
forms. The adults (Fig. 346) somewhat resemble the Muscidse, but the 
abdomen is liable to be stouter and in many cases bears numerous stiff 
bristles which are very noticeable. The eggs (or larvae in some cases) 



THE DIPTERA 



327 



are laid on caterpillars and other insects, or, in some cases, on the leaves 
which these will feed upon, and, on hatching, the maggots bore their 
way into the host and feed upon its tissues, finally killing it. The adults 
are common around flowers and also in places where plants are growing 
rankly, and there are many species. 

Family Anthomyiidse (The Anthomyiids). — This family contains 
many injurious species, the larvae of some mining in the roots and of others 
in the stems and leaves of important crop plants. Others breed in 
decaying vegetable and animal materials and excrement and from their 
habits it is suspected that they may be disease 
carriers like the house-fly. 

The Cabbage Maggot (HylefJiyia brassicce 
Bouche). — The Cabbage Maggot is a native of 
Europe but has been present in this country 
for many years. The adult (Fig. 347) is a small, 
clear-winged fly about two-tenths of an inch long, 
not often noticed or at least distinguished from 
other small flies present in the fields. Winter is 
passed as the pupa in its puparium underground, 
and also possibly to some extent as the adult, in 
protected places. At all events, the adult flies 
are present in the spring as soon as the cabbage 






Fig. 347. Fig. 348. 

Fig. 347. — Adult male and female flies of the Cabbage Maggot {Hylemyia brassicce 
Bouche). About three times natural size. {After N. Y. Agr. Exp. Sta. Bull. 419.) 

Fig. 348. — Young Cabbage Plant showing Maggots on its stem. Natural size. 
(Modified from Britton, Fourteenth RejA. Ent. Conn. Agr. Exp. Sta. 1914.) 



and other cruciferous plants are available. The eggs are now laid on 
or close to the plants. They hatch in a few days, and the maggots 
(Fig. 348) attack the stem just below the level of the ground where 
they feed for about 3 weeks, lacerating the cell walls and feeding on 
the softer tissues, using for the first process a pair of stout, black 
hooks attached at the mouth which seemingly are extremely modified 
mouth parts. When full-grown, the larvae leave the plants, enter the 
ground and form puparia from their larval skins within which they 
pupate for a period of from 12 to 18 days in most cases, after which the 
adults emerge and eggs are laid for a second generation. 



328 



APPLIED ENTOMOLOGY 



The number of generations in a season has been worked upon by 
several investigators with somewhat differing results. It seems probable, 
however, that in the latitude of New York, the insect as a rule has three 
generations though in favorable seasons four are possible, and in unfavor- 
able ones only two may occur. Presumably, the number farther north 
will usually be two, and farther south four may prove the usual number. 
Weather conditions apparently have an influence on this — hot, dry 
weather hardening the roots of the food plants so that feeding is slower 
than would otherwise be the case, and this same kind of weather also 
seems to lengthen the pupa stage. It is interesting to note that the 
insect though present in the Gulf States does not seem to be a serious pest 
south of the latitude of southern Pennsylvania. It has been found as 
far west as Colorado. 




Fig. 349. — Cabbage Plant protet-ieu ity u Lai-iKipi-i disk around its stem. {Modified from 
Brilton, Fourteenth Rept. Ent. Conn. Agr. Exp. Sta. 1914.) 

Whatever the number of generations a season, the insect seems 
able to reach the pupa stage before winter, and possibly become adult 
in some cases. 

The Cabbage Maggot is most serious as a pest on cabbages and cauli- 
flowers. It also attacks turnips, radishes, mustard and other cruciferous 
plants, however, and late generations may live more on these plants 
as the cabbage and cauliflower roots get older, tougher and less attractive 
to the insects. 

Control. — Cabbage and other plants, liable to attack while in seed- 
beds, can be protected by covering these places with screens of cheese- 
cloth. When the plants are set in the fields, tar-paper disks may be 



THE DIPT ERA 



329 



placed around their stems close to the ground (Fig. 349) and usually 
give good results. These disks may be cut by hand from ordinary tar 
paper, though where many are required, the use of a cutting stamp is 
advantageous. The piece is usually cut six-sided for economy of the 
paper, and from one corner a cut to a little beyond the center is made 
and also a short cut crossing this at the center, giving four points between 
which the stem is passed. The disk is then pushed down to the ground. 
In cultivating later, care should be taken to brush off any dirt which 
gets on the upper side of the disk as in such cases the fly often attacks 
the plant. The destruction of all the refuse of the plants on harvesting 
the crop, and also of all mustard and other cruciferous plants near by, 
is desirable to prevent further increase of the insect there before winter. 

Various other treatments have been suggested but have not given 
entire satisfaction. The tar-paper disks are not entirely effective as 
protectors, and to apply them carefully requires time, but they give the 
best results of any control method thus far discovered. 

Recently, one ounce of corrosive sublimate dissolved in 10 gal. of 
water, poured around the bases of the plants, has given quite good results. 




Fig. 350. — Adults of the Onion Maggot (Hylemyia antiqua Meig.), twice natural size. 
(From Brition, Eleventh Repl. Ent. Conn. Agr. Exp. Sla. 1911.) 



The Onion Maggot {Hylemyia antiqua Meig.) is often a serious pest, 
mining in the bulbs and quickly causing their decay. Like the Cabbage 
Maggot, it is a European insect but has been known in the United States 
for many years and is now widely distributed. Details of its life history 
are not as well known as could be desired, but it is probable that the 
insects pass the winter as pupse and perhaps as adults also. The flies 
(Fig. 350) lay their eggs on the onions soon after they come up in the 
spring, and these hatch in a few days forming whitish maggots which 
attack the bulbs and feed during a period varying according to weather 
conditions for from 2 to 4 or 5 weeks, after which they pupate in the 
ground, or, occasionally, in the outer layers of the onion itself. During 
the summer, this stage continues about 2 weeks, after which the adult 
flies appear and in about 10 days begin to lay eggs for a second generation. 

In some parts of their range there are probably only two genera- 
tions a year, but elsewhere there seem to be three. The injury caused 
by this insect when abundant is sometimes large, entire fields con- 



330 APPLIED ENTOMOLOGY 

sisting of many acres having nearly every onion affected. It varies 
greatly in importance in different years, however, there being in some 
seasons practically no maggots. 

Control. — The adult flies feed freely both before and during the 
egg-laying period. Making use of this fact, a poisoned bait spray issued, 
consisting of 3^^ oz. of white arsenic or sodium arsenate dissolved in 1 gal. 
of boiling water to which is then added from 3^^ to 1 pint of strong- 
smelling molasses. This is sprayed in coarse drops in strips across the 
field, it not being necessary to cover the entire area in this way. Repeat 
twice a week from the time the onions show until the middle of June. 
This treatment has given good results but the cost of the labor involved 
in so many applications is considerable. 

Other members of this family are frequently injurious, and, among 
these, the Seed-corn Maggot, often attacking peas and beans also, the 
Beet and Spinach Leaf-miner and the Radish Maggot may be mentioned. 
Methods of control for these insects are at present far from being as 
satisfactory as could be desired. The Lesser House-fly and several 
other small, house-inhabiting flies which belong here are also of some 
importance as probably being disease carriers. 

There are several families of extremely modified aberrant forms 
which are generally classed together as a suborder of the Diptera ca,lled 
the Pupipara. Some of these insects are winged while others are wing- 
less when adult. The majority of them suck the blood of birds or mam- 
mals though one species not thus far reported from America is found 
on the body of the honey bee. Swallows appear to be favorite hosts 
for some of these insects and bats for others, while the most familiar 
insect belonging here lives on the sheep and is commonly called the 
Sheep Tick. A number of others of the group are also wrongly called 
ticks, probably because of their color which is similar to that of some 
common ticks, their leathery external skin, and the places where they 
are found. True ticks have eight legs, however, and never have wings, 
while six legs only are present in the Pupipara as with the other insects. 

The Sheep Tick {Melophagus ovinus L.). — This pest of sheep is a 
wingless, brown insect about a quarter of an inch long. It occurs in 
most of the countries where sheep are raised and is present practically 
wherever sheep are found in the United States, though most abundant 
in the West in the large flocks. The adult lives in the fleece of the host 
except when feeding, at which time it moves to the surface of the skin 
of the animal, punctures it and sucks the blood and lymph causing irrita- 
tion which, when many of the insects are present, makes the sheep rest- 
less, preventing their feeding considerably, and resulting in their failure 
to grow and fatten as they should. 

The adult (Fig. 351) does not deposit eggs, these being retained within 
the body of the parent until they have hatched into larvae (Fig. 352) and 



THE DJPTERA 



331 




Fig. 351. — Adult engorged female Sheep Tick (Melophagus ovinus L.), greatly enlarged. 
{From Marion Inea, Bur. An. Ind., U. S. D. A. Farm. Bull. 798.) 




Fig. 352. — Young Sheep Tick just after emerging from its puparium. Greatly enlarged. 
{From Marion Imes, Bur. An. Ind., U. S. D. A. Farm. Bull. 798.) 



332 APPLIED ENTOMOLOGY 

during this period being nourished by the secretions from glands in the 
body of the parent. When the development of the larva has been nearly 
completed, it leaves the parent and is then covered by a soft, white 
membrane which, after some hours, turns brown and hard and becomes a 
puparium within which the animal pupates for a period of from 19 to 
24 days after which the adult emerges. After about 10 to 14 days more, 
their first pupae appear. A pupa is produced by a female every 7 or 8 
days, 12 to 15 being about the usual number in all per individual. 

Control. — The most widespread method for controlling these insects 
is by dipping the sheep in some material which will kill the ticks. Some of 
the dips used for this purpose are coal-tar-creosote, cresol, nicotine and 
lime-sulfur-arsenic. Selection of the best dip for the purpose must 
be determined by the availability of soft water, ease of obtaining the 
materials and other local factors. In general, two dippings are necessary 
and, if this is done during the early fall, these should be 24 days apart. 
Where shearing is done in the spring, the dipping should be in July and 
August unless the lambs become thickly infested soon after shearing, in 
which case dipping should be as soon as the shear cuts heal. Many 
details connected with dipping make it necessary to become thoroughly 
acquainted with the process before treatment is actually attempted, 
if the best results are desired. 



CHAPTER XXXII 



THE SIPHONAPTERA 



The Siphonaptera or Fleas are curious, small insects ranging from 
about a twentieth to a sixth of an inch long. They are evidently related 
to the flies in many ways but are much modified. Most of the members 
of the group have their bodies laterally compressed so that they are 
narrow (Fig. 353). The head is not sharply separated from the botly and 
the antennae are short and stout. The mouth parts are for piercing 
and sucking, and modified in a different way from those of other insects 
which feed in this manner. While the identity of the various parts has 




Fig. .35.3. — Adult Cat and Dog Flea (Ctenocephalus cants Curtis), greatly enlarged. 

(Original.) 

not been conclusively proven, it seems probable that a long median 
pricking structure is the labrum or else the hypopharynx; a pair of 
similar structures are the mandibles; a pair of rather short, stout struc- 
tures at the sides, each with a palpus, are the maxillae, and that the 
labium is represented by a rather stout basal portion bearing two long 
segmented pieces, perhaps the palpi, so shaped as together to form a 
loose sheath for the piercing parts. Compound eyes appear to be 
absent. 

Backward-projecting spines occur on the body, largely at least, 
preventing backward movements between the hairs on the body of the 

333 



334 APPLIED ENTOMOLOGY 

host animal. Rows of stout spines may be present on the head just 
above the mouth or on the pronotum or in both places. These are called 
tsenidia and are useful in identifying the species. The legs are long 
and powerful. Wings are absent but fiat scales present on the meso- 
and metathorax are generally regarded as their rudiments. The larvae 
are worm-like, with chewing mouth parts and pupate within a cocoon. 

The characters distinguishing these insects are: 

Insects which as adults have their bodies strongly compressed sideways; 
are without wings and compound eyes hut have legs. Mouth parts for pierc- 
ing and sucking. Larvce worm-like. Metamorphosis complete. 

Adult fleas feed entirely upon the blood of mammals and birds, 
but while each species has what may be termed its preferred host, there 
seems to be some latitude in this, and other animals may also be attacked. 

The eggs are laid loosely among the hairs of the host and drop to 
the ground where they hatch. The larvse which are slender, whitish, 
and rather worm-like, with chewing mouth parts, feed on decaying vege- 
table and animal matter for a period varying from a few days to several 
months. When feeding is completed, the larva spins a silken cocoon in 
which it pupates. Here it may remain only a few days or for a time 
which may be more than a year, according to circumstances, before 
emerging as the adult. The adults in hot weather and with no food will 
live only a few days but when food is available they may live a month 
or even nearly a year. Winter in the North is usually spent in one or 
another of the early stages, but in the South the adults may be present 
on their hosts at any time. 

Hot, dry weather is not favorable to the rapid breeding of these 
insects but, in damp, rainy weather, they increase rapidly, particularly 
in sandy localities as the moisture there is more uniform where the early 
stages live, though too much moisture is injurious to them. 

Fleas are mainly household pests, coming in on cats and dogs, the cat 
flea being the most common generally, though in the West and South 
the human flea is also abundant. The eggs dropped by the fleas fall to 
the floors and the larvae feed on any material found under rugs and mat- 
tings, in floor cracks and similar places, and, on reaching maturity, attack 
the first animal they can reach. 

Various animals besides those already mentioned serve as hosts. 
Among them are hogs, poultry and other birds. Horses, cattle and 
sheep are not often attacked. 

Fleas have become of importance to man aside from their attacks on 
his person with the discovery that they may carry the germs of the 
bubonic plague. This much dreaded disease with its high mortality 
caused by Bacillus pestis occurs in rats' blood, and by feeding on this 
the flea brings the germs into its own body. When a flea attacks a 
person, it often ejects partly digested blood and also feces near the 



THE SIPHON APTERA 335 

"bite" and if, while the wound is still open, this place is rubbed or 
scratched the germs are liable to thus be introduced into the blood of the 
person. Their absence from the mouth parts and the saliva of the flea 
so far as observations have yet gone indicates therefore that inoculation 
with the germs from fleas is accidental, but as most persons generally- 
scratch a flea bite, it is at least frequent enough to produce many cases 
of the disease. In California, the disease has also been found in ground 
squirrels and in one species at least of squirrel flea so that these fleas are 
also a menace to man. 

Control of Fleas. — In houses, flea control must be both by destroying 
the adults and also the early stages. On small animals which are 
infested, a thorough washing with a soap coal-tar creosote material 
used as a "stock dip" of which a number of kinds arc for sale gives 
satisfactory results if fhe animal is thoroughly scrubbed and partic- 
ular care given to see that the head — to which the insects collect when 
the animal is put into the wash — shall receive particular attention. 
Keep the animal in the wash for five to ten minutes. If it has a tender 
skin, this treatment may be followed by washing in warm water with 
soap. 

Other ways for treating infested animals are by rubbing powdered 
naphthaline into the hair, or by dusting thoroughly with Pyrethrum. 
Give these treatments over paper on which the stupified fleas fall so 
that they may be gathered and burned. Animals which are attacked by 
fleas should not be allowed under houses as is so often the case in the South 
when no cellars are present and the house is placed on low posts. In such 
cases, these places are excellent locations for fleas to breed and when adult 
enter the houses. 

To destroy the early stages successfully, the food of the larvae should 
be kept in mind and all such material be removed. Thorough cleaning, 
removing all dust, much of which is flea food; soaking cracks, where it 
might gather, with kerosene; airing and beating rugs, carpets, straw mat- 
tings and, in fact, all floor coverings, are important control measures. 

There are other ways in which fleas may be controlled. One is to 
sprinkle 5 lb. of flake naphthaline over the floor of an infested room and 
close tightly for 24 hr. ; then open and sweep it into any other room needing 
treatment and manage in the same way. Several rooms can be treated 
with the same material. Fumigation with sulfur, using 4 lb. to each 1,000 
cu. ft. of space if the young are present and 2 to 3 lb. if only adult 
fleas are involved, the fumigation to continue 12 hr., is also, a successful 
control. Cellars infested should be thoroughly cleaned and whitewash 
used freely. 

Flea "bites" if troublesome may be relieved by the use of carbolated 
vaseline, camphor, or a 3 per cent solution of carbolic acid in water. 



336 



APPLIED ENTOMOLOGY 



One of the fleas commonly called the "sticktight" flea {Echidnophaga galli- 
nacea Westw.) is a rather important pest of fowls in the South and Southwest, 
causing trouble as far north as Kansas. These fleas gather chiefly on the heads 
of the birds where they are noticeable around the eyes and on the wattles and 
comb, but may occur elsewhere on the animal. Chickens are often killed by 
these fleas but older fowls are more resistant. This flea differs from most other 
species by remaining most of its life on the fowl, whence its common name. 

Where the infestation is severe, the use of carbolated vaseline, or a mixture of 
lard 2 parts and kerosene 1 part, carefully applied only to the places where the 
fleas are on the fowl; the destruction of rats which also harbor this pest, and a 
thorough cleaning of the poultry houses are desirable. Salt on the soil where the 
fleas are breeding, followed by a liberal application of water by sprinkling, this 
last repeated two or three times a week, will destroy the young, but no salt 
should be left for the poultry to feed upon. 

One species of flea differs somewhat in its habits from most of these 
insects. It is known as the Chigoe or Jigger fiea {Tunga pene- 
trans L.) and occurs in the tropical and subtropical portions of America 
and also in Africa and India. It should not be confused with a tiny mite 
(Class Arachnida) which has somewhat similar habits and is found as far 
north as Massachusetts and I^ake Erie, which is abundant on bushes, and 
which on man burrows into the skin causing considerable irritation. 




Fig. 354. — Chigoe (Tunga penetrans Ti.): a, an Unfertilized female; b, onefertilized, 
which has penetrated the skin and is beginning to enlarge; c, one enormously enlarged 
by the development of eggs. All enlarged. (From Berlese.) 



The Chigoe is found on domestic animals, birds and man. The 
female (Fig. 354a) is at first about a twenty-fifth of an inch long but its 
abdomen may later become as large as a small pea. The adults move 
about but when the female has been fertilized it burrows into the skin 
of the host and its body begins to enlarge (Fig. 3546 and c) by the develop- 
ment of eggs, causing a painful wound like an ulcer. The eggs are expelled 
into this ulcer or may fall to the ground but, in either case, hatch in a few 
days, and those in the wound then work out and drop to the ground. 

The regions usually attacked in persons are the bare feet, though no 
part of the body is entirely free from the danger of being attacked. Pus 



THE SIPHON APTERA 337 

is produced in the wounds and when many of the fleas are present the 
ulcers may run together and cause serious results. Protection from these 
pests is best obtained by keeping the floors clean, using naphthaline as 
recommended above; cleaning floors and walls with kerosene; and wearing 
shoes or other foot coverings to keep the insects from reaching the skin. 
When the fleas are already burrowing they may be removed by the use of 
a needle which has been sterilized by passing it through a flame, followed 
by a dressing of the wound. A drop of turpentine at each spot attacked 
will kill the fleas and, if ulceration has not gone too far, the wound will 
generally ulcerate enough more to expel the animal and then gradually 
heal. 

Fleas occur in nearly all parts of the world, and, though less than 500 
kinds are known, their habits and their relation to disease make them an 
important group of insects. 



22 



CHAPTER XXXIII 
THE HYMENOPTERA 

The insects which belong in this large order have no general common 
name, but many of them are well known as bees, ants and wasps. The 
larger portion of the group, however, consists of small insects seldom 
noticed except by those looking for them. 

Most Hymenoptera have wings when adult. These are four in num- 
ber, membranous, and the front pair is the larger. They have rather few 
cross veins as a rule, and in some cases nearly all the veins are missing. 
The two wings on the same side of the body are united by a row of hooks 
along the middle part of the costa of the hind wing, which catch in a fold 
of the membrane on the hinder margin of the wing in front, the two wings 
in this way acting together and much as though they were one. The 
structures uniting them are called the frenal hooks or hamuli, and the 
frenal fold. 

The body in insects of '4iis order may be quite large and stout, as in 
the bumblebees; or long, bemg two or more inches in length in some trop- 
ical wasps, but most of them are much smaller insects and in some the 
body may be only about a fiftieth of an inch long and the entire animal 
almost microscopic in size. The first abdominal segment is very closely 
and firmly joined to the thorax, to which it apparently belongs. In a 
few families the front end of the second abdominal segment is as large as 
the rest of this portion, and the connection between the first and second 
segments is full-sized, but in most of the groups the front end of the second 
segment is constricted to form a small, stalk, pedicel, or petiole which 
connects the rest of the abdomen with the first segment. This condition 
is a deceptive one, leading to the idea that the constriction is, as is true 
of most other insects, between the thorax and abdomen rather than be- 
tween the first and second segments of the latter. The first segment, 
closely joined to the thorax is called the propodeum or median segment. 
The petiole in nearly all cases joins the propodeum close to the lower side 
of the body. 

Over the base of each fore wing except in the ants, is a small, arched 
scale called a tegula, which roofs over the place where this wing articulates 
with the body. 

In the female Hymenoptera an ovipositor, used either for making 
holes in which to deposit eggs, or modified to become a weapon, is almost 
always present. When developed for its original purpose as an organ 

338 



THE HYMENOPTERA 339 

connected with egg-laying, it may have projections along its lower edge 
and be used like a saw to cut slits in leaves or other structures in which 
to insert the eggs. In other cases it becomes a sort of boring organ used 
in making holes in leaves, stems, wood, or animals, in which the eggs are 
placed. Sometimes the ovipositor is very prominent and is not retractile, 
while in other species it can be drawn entirely within the body. In a 
large section of the order, however, regarded as containing the more 
highly developed members of the group, deposition of the eggs is not 
within objects but on surfaces, and a hole being no longer needed, the 
ovipositor has become modified in most cases, glands connected with it 
produce a more or less poisonous fluid (possibly it is more or less poison- 
ous in the lower forms also) and the sting is thus produced, a structure no 
longer needed for its original purpose having been transformed into a 
weapon for defense. In the ants, however, various degrees of reduction of 
this structure occur, some ants having no stinging power whatever while a 
few are quite effective in this way. From these facts the reason why drone 
bees and the males of the other Hymenoptera arc harmless, is evident. 

The two sections of the order thus distinguished, are called the 
Terebrantia or boring, and the Aculeata or stinging Hymenoptera. 
Another distinction also separating these divisions may be seen by an 
examination, of the mouth parts. In the T'^rebrantia these are quite 
typical chewing organs, but in the Aculeat*" the maxillae and labium 
have been modified to form organs for suc.vmg and lapping up fluids, 
though the amount of this modification differs in different families. 
A third distinguishing feature is that in the Terebrantia the hind leg 
has two trochanters while in nearly all the Aculeata there is only one. 

Development in this order is by a complete metamorphosis. The 
larvae differ much in appearance in the various families, some feeding 
on leaves and greatly resembling caterpillars. Others are borers in 
wood and are modified to adapt them to life under such conditions. 
Still others, particularly those which are parasitic within the bodies of 
other insects, may be so changed as to make it seem almost impossible 
that they can be insect larvae. Many of those living on food provided 
for them during this stage of their existence greatly resemble and are 
sometimes called maggots. At pupation a marked change in appearance 
takes place, antennae, legs, wing stubs and body characters nearly like 
those of the adults now showing, and the legs and antennae project, en- 
cased by sheaths of the pupa skin, the pupa in this order being a pupa 
libera as already described for some beetles (see page 99, and Fig. 30). 

The characters by which Hymenoptera may be recognized are: 

Insects which when adult have in most cases, four membranous wings 
with few or even no cross veins, the hinder pair the smaller. Mouth parts 
for chewing, or for chewing and also for sucking. The females have in nearly 
all cases either an ovipositor or a sting. The metamorphosis is complete. 



340 



APPLIED ENTOMOLOGY 



The Hymenoptera are important from an economic standpoint. A 
rather small number are injurious, destroying crops of various kinds 
but the majority are either directly or indirectly beneficial, as parasites 
of destructive insects, or by aiding in the fertilization of flowers, and in 
the case of the honey bees by the value to man of their products. 

There is a great diversity of structure in the order, which has led 
to the establishment of many families which fall into about 10 larger 
divisions, generally called Superfamilies, and these may serve as the 
basis for more detailed consideration. 

Superfamily Tenthredinoidea (The Saw-flies and Stem Borers). — 
This group is one of the divisions of the Terebrantia as already described, 
its members having no constriction of the abdomen. Most of the families 
belonging here are leaf-feeders and their eggs are usually laid in slits in 
the leaves sawed by the ovipositors of the adult females. Some families, 
however, have the ovipositor constructed for boring and they make 
holes, either in herbaceous or woody stems, in whiqh to deposit their 
eggs. 

The plant-feeders are spoken of in a general way as saw-flies and all 
are injurious to the plants they live on, though of course many of these 

are of little or no importance to 
man, but a few injure various 
crop-producing plants. 

The Currant Worm (Pteronidea 
rihesii Scop.). — This common in- 
jurious saw-fly is a native of Europe 
but has been in this country for 
many years and is widely dis- 
tributed. It feeds on the leaves 
of wild and cultivated currants 
and to some • extent, on those of 
gooseberries also, and when abund- 
ant the plants are quickly and 
thoroughly stripped of their foliage 
which checks or almost entirely prevents the 




Fig. 355. — Currant Worm {Pteronidea 
ribesii Scop.), adult and larvae, about natural 
size. (From Minn. Agr. Exp. Sta. Bull. 84.) 



soon after it develops 
production of the fruit. 

The adult saw-fly (Fig. 355) is about a third of an inch long, with a 
pale or reddish-yellow, rather stout body with blackish spots. It passes 
the winter in the ground within an oval cocoon, rather papery in texture 
and brown in color. In spring, about when the currant leaves become 
partly developed, the adults begin to emerge from their cocoons and the 
females lay their eggs in rows on the leaves, generally along the veins on 
the underside. The larvse, at first very small and whitish, feed and grow 
rapidly, and when full-grown are nearly three quarters of an inch long, 
greenish in color and shaded with yellowish at both ends. During the 



THE HYMENOPTERA 



341 



intermediate larval instars the green color of the body is modified by the 
presence of many black spots. After feeding from 2 to 3 weeks the larvae 
crawl down to the ground and pupate, the cocoons resembling those al- 
ready described. Adults from these pupae appear in late June or July 
and lay eggs for a second generation, and in some cases a few of the 
insects have a third generation before winter. The second and third 
generations (when present) do not attract much attention generally, as 
interest in the currants in most cases ceases for the season with the 
gathering of the crop. 

Control. — Spray the currants as soon as the leaves have developed 
or as soon as the "worms" appear, with arsenate of lead, standard 
formula or a little weaker. If treatment is necessary after the fruit 
has begun to turn red, dust fresh hellebore over the plants, using 1 lb. of 
hellebore thoroughly mixed with about 5 lb. of air-slaked lime or flour. 
The great difficulty in controlling 
these pests is that the adults ap- 
pear and lay their eggs during a 
rather long period and it is often 
necessary to spray for those larvae 
which appear early, before all the 
leaves are fully developed. Ac- 
cordingly, those leaves which come 
out after the spray has been applied 
are not protected and larvae ap- 
pearing afterwards can feed on 
them without being poisoned, and 
a second spray is often needed on 
this account. 




Fig. 356. — Pear Slug {Caliroa cerasi L.): 
a, adult; b, larva with slime removed; c, 
larva from above, coveredby its slime; d, 
leaf showing work of the insect and with 
larvae present: a, b and c much enlarged; 
d, somewhat reduced. (From Berlese, 

modified from U. S. D. A. Div. Ent. 

Circ. 26.) 



The Pear Slug (laliroa cerasi .L). 
— This insect feedson the leaves 
of the pear, plum and cherry, and 
though a native of Europe is now 
found almost everywhere in this 
Country (Fig. 356). 

The adult is a saw-fly about a fifth of an inch long, with a black body. It 
appears after the leaves develop in spring and lays its eggs in slits sawed in the 
leaves, forming a sort of blister at each place. The larvae soon produce a dark- 
brown glossy slime which covers them and conceals their true outline, making 
them somewhat similar to soft snails in appearance. They feed on the leaf tissue, 
skeletonizing it, and molt four times. After the fourth molt the slime disappears 
and the larva is orange-yellow and does not feed. It now passes to the ground in 
which it pupates. A second generation follows, but a few of the pupse remain 
unchanged in the ground until the following spring. In the South there are three 
generations, at least in some cases. 



342 



APPLIED ENTOMOLOGY 



Control. — Spraying with arsenate of lead, standard formula; Nicotine sulfate 
40 per cent, 1 pt. in 100 gal. of water, with 3 or 4 lb. of soap; 1 oz. of white helle- 
bore in 3 gal. of water; or dusting with freshly slaked lime, are effective treatments 
for this insect, but it is not very often abundant enough to call for the use of 
control measures. 

A similar saw-fly often attacks the rose, feeding on the leaves, its dark-colored 
and slimy, though small, larvse being very noticeable when abundant. When 
treatment is necessary the methods given for the pear slug are equally effective 
with this insect. 

A few of the stem and wood borers in this superfamily are of considerable 
importance, but most of them are seldom noticed. The Wheat-stem borer 
(Cephns pygmceus L.) in the East and the Western grass-stem borer {Cephus 
cinctus Nort.) in the West often attack growing wheat. The adult (Fig. 357) 




Fig. 357. — Western Grass-stem Borer (C'ephut< cinctus Nort.): 3, base of wheat plant 
showing larva m winter position; 5, adult Saw-fly; 6, full-grown larva. All natural size. 
{Modified from Can. Dept. Agr. Ent. Branch, Bull. 11.) 



jjunctures the wheat stem in the spring and deposits an egg inside the stalk and 
the larva which soon hatches, tunnels in the stem and as the grain ripens, 
works its way downward, and by harvesting time most of them have reached 
the roots. They then prepare for winter, cutting the stalk partly off, generally 
less than an inch above the surface of the ground. Each now plugs the cavity 
of the stem below this point for a short distance, leaving about half an inch of 
space between the plug and the lower end of the cavity, in which it spins a cocoon. 
The larva winters thus, pupates in March or April in New York at least, and 
the adult appears in May. The life history of the western species is much the 
same. 

Where grass-seed is not planted with the wheat, plowing the stubble under, 
deeply, at any time between harvest and the following May, or burning the stub- 
ble when this is possible, are two fairly efficient methods of control. Where it is 
desired to lay down a field to grass and the insect is abundant it would be better 
where practicable to use oats rather than wheat with the grass-seed. 



THE HYMENOPTERA 



343 



One of the stem borers attacks currant stems. The adult girdles the stem after 
laying its egg, and the larva feeds below the girdled place, which shows plainly, 
the part above wilting or breaking over. Cutting off such stems as soon as they 
are seen, eight or ten inches below the girdled place, will control this insect. 

Most of the borers of this superfamily which tunnel in wood are 
generally called Horn-tails, the straight, stiff ovipositor somewhat 
suggesting a horn. Various trees, both deciduous and evergreen, are 
attacked by different species, and the circular exit holes of the borers 
after they have become adult permit the entrance of moisture and the 
spores of fungi, thus providing starting places for decay. Healthy, 
vigorous trees are seldom attacked, but the death of others is hastened 
by these insects. One species 
known as the Pigeon Tremex 
(Tremex columba L.) bores in the 
maple, apple, pear, elm, beech, oak 
and sycamore. It varies from 
three-quarters of an inch to twice 
as much in length (Fig. 358) and 
its body is cylindrical and nearly 
as large as a lead pencil. Its color 
varies from nearly black with 
yellow spots on the abdomen to 
yellow with some black marks. 
This insect is often noticed on the 
tree trunks during the summer 
months. The larva tunnels its 
course through the wood, going 

sometimes several inches into the tree, but as the end of its feeding 
period approaches, turns outward and makes a hole to the outside, 
leaving only a thin piece of bark to close the opening. It then goes 
back into the hole a short distance to pupate and the adult on emer- 
gence gnaws away the piece of bark and escapes from the tree. An 
interesting and remarkable looking parasite of this insect will be considered 
later in the chapter. 

Superfamily Ichneumonoidea (The Ichneumon Flies). — In this very 
large and important group the insects have the abdomen constricted as 
already described, between the propodeum and the second abdominal 
segment. In one family (the Evaniidae or Ensign flies) of rather small 
insects (Fig. 359) the petiole of the second segment does not join the pro- 
podeum near the lower side of the body but near the upper surface, giv- 
ing these insects a very peculiar appearance. 

The Ichneumon flies (Fig. 360) are all parasites, attacking Lepidop- 
tera, Coleoptera, Diptera, and some Homoptera ,Orthoptera and Hymen- 




FiG. 358. — Pigeon Tremex (Tremex columba 
L.), somewhat reduced. (Original.) 



344 



APPLIED ENTOMOLOGY 



optera, and also Spiders in their early stages, at least in most cases, and 
a few are injurious as they are parasites of beneficial forms. Thus 
among the Coleoptera parasitized are some of the Lady beetles. In 
other cases it is the parasites themselves which are parasitized. In 
this last case the destruction of a beneficial parasite by another makes 
the latter an injurious insect. There are also some which appear to 
attack the parasites of the parasites, which places these last as beneficial 
in their turn. Primary parasites attack non-parasitic forms; secondary 
or hyperparasites attack primary ones; tertiary parasites attack the 
secondary ones, etc. 





Fig. 359. Fig. 360. 

Fig. 359. — An Evaniid {Brachygaster minutus Oliv.), about five times natural size. 
(Modified from Kieffer.) 

Fig. 360. — Example of an Ichneumon Fly (Ophion), natural size. {Original.) 



The importance of the Ichneumon flies as parasites is very great as 
they are abundant and destroy enormous numbers of injurious forms 
each year. One group devotes its attention to plant lice, puncturing 
the bodies of these insects and laying an egg in each puncture. The 
tissues of the plant louse are fed upon by the parasite and the body of the 
host gradually becomes brown, swollen and rather globular, and it dies, 
holding on to the place where it was feeding at the time of its death. 
After pupation within the body of the host, the adult parasite cuts a 
circular opening in the surface of its host and escapes, and plant lice 
bodies, swollen, brown, and with a hole in each are abundant when these 
insects occur in large numbers. As each parasite obtains all the food 
necessary for its entire development from the body of a single louse, these 
insects are naturally extremely small (See Figs. 199 and 200). 

Another Ichneumon fly which is often noticed has a body an inch and 
a half or more long and an ovipositor often over three inches and which has 
been recorded in a few cases as nearly six inches in length. There are two 
kinds of about this size, one with a black body and a few yellow spots, 
the other brown with yellow markings, while other and smaller species 
also occur. These insects attack the Horn-tails already described and 



THE HYMENOPTERA 



345 



may often be seen during the summer on trees in which Horn-tail larvse 
are present. These Ichneumon flies are called the "Long-tailed Thales- 
sas." The female Thalessa (Fig. 361) crawls about over the trunk of a 
tree which in some way she discovers is infested by Horn-tails, until a 
satisfactory place is found, when she settles at that point and begins to 
force her ovipositor into the bark and wood. The length of the ovipositor 




Fig. 301. — Long-tailed Thalessa {Megarhyssa lunalor Fab.): a, larva; c, pupa; e, adult 
female;/, side view of abdomen of adult female, showing attachment of ovipositor; g, adult 
male. About natural size. {Modified from Felt, N. Y. State Mus. Mem. S; after Riley.) 

is suggestive of the distance it must be pushed in, in some cases, to reach 
the tunnel of the Horn-tail larva, and it seems almost impossible for 
such a slender structure to be forced so far through hard wood. When 
the tunnel of the Horn-tail is reached, the Thalessa lays an egg in it and 
then draws its ovipositor out of the tree. Sometimes this process results 
in the death of the Thalessa, the ovipositor becoming so firmly fixed 







^^ 




// 


>.^ 


~\^ 






V 


% 


1 



346 APPLIED ENTOMOLOGY 

in the wood either on its way in, or during the withdrawal, that it cannot 
be removed and the Thalessa dies. 

The egg left in the tunnel of the Horn-tail soon hatches and the larva 
travels along the burrow until it finds the borer, to which it attaches 
itself, and feeds upon its juices. It is probable that death of the Horn- 
tail is not permitted as a result of this feeding, before the host has pre- 
pared an outlet to the surface of the trunk for its escape, as it does not 
seem likely that the adult Thalessa could turinel its way out successfully. 
Superfamihj Cynipoidea (The Gall Insects). — This group of small 
insects (Fig. 362) includes species having very diversified habits, but the 
majority of them pass their early stages within abnormal growths on 

plants, called galls, which develop in connection 
with their presence. Some insects other than 
those of this group also produce galls, particu- 
larly many of the dipterous family Itonididse, 
but the greater number of the more noticeable 
galls are produced by Cynipids. 

The cause of the production of the gall has 
^ „„.-. „ , , been much discussed, some investigators claiming 

ria. 362. — Example of a 

Gall insect {Trigonaspis that at the time the female insect punctures the 
mecjaptera Panz.) about pi^nt for egg-laying she also injects a little 

twioe natural size. {Reduced ' oo ^ o j 

from Henneguy.) poison into the wouud which stimulates the 

plant cells of that region to grow in an abnormal 
manner. But the general belief now seems to be that the larva when 
it hatches gives the stimulus for this abnormal growth, either by its 
presence as a moving body, by its gnawing, or by its pouring o\it of 
irritating fluids. 

The gall includes either one larva or many, according to the species 
concerned. It stops its growth about the time the larva finishes feeding, 
and dries, forming a protective covering within which the insect pupates 
and escapes subsequently by gnawing its way out. 

In some species such an adult will attack a totally different kind of 
plant from the one it itself fed upon and the gall produced will be entii-ely 
different from the other. Adults from such galls will deposit their eggs 
in plants of the first kind, however, giving us a series of generations in 
which two different kinds of plants alternate in supplying food. This 
may be complicated by one generation consisting only of females, the 
other evidently being derived by agamic reproduction (parthenogenesis). 

Galls may occur on roots, stems, twigs or leaves, and the type of gall 
produced is always the same on any one kind of plant, for the same spe- 
cies (Fig. 363), so t]iat a student of the subject can tell from the gall 
alone, the species which produced it, in nearly every case: one found on 
oak leaves is nearly an inch in diameter, globular, with a parchment-like 
covering, and is often called an "oak apple." Within the outer covering 



THE HYMENOPTERA 



347 



is a mass of radiating fibers and at the center a small cell in which the 
insect lives. Protuberances of various forms on the leaves of many kinds 
of plants are produced by different species of these insects. 

Gall insects are often not alone in their habitations. Some members 
of the same superfamily as the gall-makers are frequently found in the 
galls, living as "guests," profiting by the work of the producers of the 
galls but not injuring them in any way. These are usually called in- 
quilines and often greatly resemble their hosts. In addition to the 
inquilines, parasites not only of the host but also of the various kinds of 
in(}uilines may also be present, adding greatly to the population of the 
gall. Some of these may be of the same superfamily as their hosts. 
Kieffer lists 10 species of guests and 41 species of parasites which he 
obtained from a root gall on oak, besides the gall maker itself! 




Fig. 363. — Various types of Galls, about natural size. {Original.) 



Galls are not usually of any great economic importance, for though 
they may injure the appearance of a plant or tree for two or three sea- 
sons, and also check its growth somewhat, the abundance of parasites 
usually stops the work of the gall makers before serious injury has been 
accomplished. 

Superfamily Chalcidoidea (The Chalcid Flies). — This is an extremely 
large group, containing thousands of kinds of insects, most of which are 
very small, and a few are only about a fiftieth of an inch long. Some of 
them live in galls, parasitic either on the gall maker or on inquilines: 
others are parasitic on various insects, parasitizing the egg, larva or 
nymph, pupa, or adult according to the species; and a few are plant 
feeders of more or less economic importance. The wings, except in some 
wingless species, have very few veins, the most prominent one running 
out from the body about half way to the tip, then bending forward to the 
costa, after which it bends back into the wing a short distance and ends. 



348 APPLIED ENTOMOLOGY 

This is the only one in a great many cases, though a few other weaker 
veins are often present. 

The plant feeders in this group produce small galls or at least swellings 
of the portion of the plant where they live, and one or two, by attacking 
crop plants, are of importance to man. A number of species of the genus 
Harmolita attack different kinds of small grains such as wheat, oats and 
barley, and at times do considerable injury. 

The Wheat Straw -worm {Harmolita grande Riley). — This insect extends from 
New York to Colorado and from the Great Lakes to Virginia and Tennessee and 
is also present on the Pacific Coast, but has thus far been of little importance east 
of the Mississippi River. The adult is a tiny black insect somewhat resembling 
an ant, with red eyes, and legs banded with yellow. One generation has wings; 
the other is wingless. 

The winter is spent in the pupa stage in the stubble of wheat fields and the 
adults emerge in April and May in the more northerly states; earlier in the South. 
These are the wingless forms and are very small. They lay their eggs in the 
wheat plants which at this time have grown only a short distance above ground, 
and the larva feeds in the short stem, usually producing a swelling there, and 
when full-grown it has worked its way to the crown of the plant where it entirely 
consumes the head, thus preventing the formation of any grain. By the last of 
May these larvae have completed their feeding and pass through a brief pupal 
period, the adults — winged in this generation — emerging in early May in the 
South, and in June in the North. These individuals fly freely and spread to other 
fields. Eggs are now laid in this wheat, preferably well up toward the head 
where the joints are most tender and juicy. The larvae from these eggs feed 
and reduce the yield of wheat by consuming nourishment which would otherwise 
go to the grain. Full growth has been obtained before the straw hardens, and 
pupation occurs during the fall. Whether the insects will be taken off in the straw 
or remain behind in the stubble depends on the degree of advancement of the 
plants, and the height above ground of the cutting. 

Control. — Crop rotation, raising no wheat on the same land for 2 years in 
succession is a good treatment, as the wingless generation cannot migrate to other 
fields. Volunteer wheat in or near such fields should of course be destroyed if 
the rotation is to be most effective. Burning over, or plowing under of the 
stubble is also desirable, though less effective. Winter and spring wheat should 
never be grown near each other. 

The Wheat Joint-worm {Harmolita tritici Fitch, Fig. 364). — This is a species 
closely related to the last, found throughout the East to the Mississippi River and 
south to about the same limits as the other species. Its life history differs from 
that of the Wheat Straw-worm in there being only one generation a year. Winter 
is passed as the larva in wheat straw or in the stems of various grasses, and the 
adults appear in May or June. Eggs are deposited as high up the wheat stems 
as the adult can find an uncovered stem. The larva> have completed their feeding 
by harvest-time but do not pupate until the following spring. Apparently a 
rotation of crops, and care that waste lands, fence borders, etc., do not provide 
grass stems in which it can breed and winter are about our only methods for the 



THE HYMENOPTERA 



349 



control of this pest. The injury these two species of Harmolita do varies all the 
way from very little to an almost entire loss of the crop. 

Where clover seed production is extensive, considerable injury to the crop is 
often caused by the Clover-seed Chalcid (Bruchophagits funebris How.). Red and 




Fig. 364. — Adult female Wheat Joint-worm {Harmolita tritici Fitch), greatly enlarged. 
{From U. S. D. A. Farm. Bull. 1006.) 

crimson clover, and alfalfa to some extent, are attacked by this tiny insect which 
feeds as a larva within the seed. Another species works in a somewhat similar 
way in apple seeds. 

A Chalcid whose presence is essential in connection with the produc- 
tion of Smyrna figs, which is now becoming an important industry in 
some parts of this country, is oi interest for that reason. This insect, 




Fig. 365. — Fig fertilizer {Blastophaga grossorum Grav.). A, male, about fourteen times 
natural size; B, female, about ten times natural size. {Reduced from Hennegny.) 

known as Blastophaga grossorum Grav. (Fig. 365), and its relation to fig 
production, are well described by Kellogg as follows: 

"The male Blastophagas are grotesque, wingless, nearly eyeless creatures 
which never leave the fig in which they are bred, but the females are winged and 



350 APPLIED ENTOMOLOGY 

fly freely about among the trees. A fig is a hollow, thick, and fleshy-walled 
receptacle in which are situated, thickly crowded over the inner surface, the 
minute flowers. The only entrance into the receptacle (or fig) is a tiny opening 
at the blunt free end of the young fig, and even this orifice is closely guarded by 
scales that nearly close it. The eggs are laid by the females at the base of the 
little flowers in certain figs. The hatching larvae produce little galls in which 
they lie, feeding and developing. They pupate within the galls, and the wingless 
males when they issue do not leave the interior of the fig, but crawl about over 
the galls, puncturing those in which females lie, and thrusting the tip of the 
abdomen through the puncture and fertilizing the females. The fertilized winged 
female gnaws out of the galls, and leaves the fig through the small opening at the 
blunt free end. She flies among the trees seeking young figs, into which she 
crawls, and where she lays her eggs at the bases of as many flowers as possible. 
But it is only the wild, inedible, or 'caprifigs' that serve her purpose. The 
flowers of the cultivated Smyrna seem to offer no suitable egg-laying ground and 
in them no eggs are laid. But as the female walks anxiously about inside the 
fig, seeking for a suitable place, she dusts all the female flowers with pollen 
brought on her body from the male flowers of the caprifig from which she came, 
and thus fertilizes them. This process is called caprification. Without it no 
Smyrna fig has its flowers fertilized and its seeds 'set.' It is the development 
of the seeds with the accompanying swelling of the fleshy receptacle and the 
storing of sugar in it that makes the Smyrna fig so pleasant to the palate. The 
trees may grow large and bear quantities of fruit, but if the fig (really the fig- 
flowers) are not caprified, the size, sweetness, and nutty flavor of the perfect 
fruit are lacking. To insure caprification, branches laden with caprifigs con- 
taining Blastophagas just about to issue are suspended artifically among the 
branches of the Smyrna fig. Of course the female Blastophaga entering a 
Smyrna fig and dying there leaves no progeny, for she lays no eggs. It is there- 
fore necessary to maintain a plantation of caprifigs in or near the Smyrna orchard. 
These bear three crops or generations of figs: one, the 'profichi,' ripening in the 
spring; another, the 'mammoni,' ripening in the late summer; and the third, 
or 'mammse' generation, which hangs on the tree through the winter. By 
means of these successive generations of caprifigs a series of three generations 
(or sometimes four) of Blastophaga appear each year." 

The great importance of the Superfamily Chalcidoidea to man does 
not rest either upon the importance of its destructive members or upon 
the Blastophaga, but on the enormous number of parasitic forms included 
in the group. These work in various ways as has already been indicated, 
but only one can be considered here. It is a parasite on various species 
of butterflies, particularly the Cabbage butterflies, and is known as 
Pteromalus puparum L., having no common name. 

This insect (Fig. 366) is probably a native of Europe. It was noticed 
here about 1870 and is now present wherever its host insects occur and 
frequently destroys great numbers of them. 

The adult has a green body about a tenth of an inch long. The 
female punctures the chrysalids of the host and lays her eggs within the 



THE HYMENOPTERA 



351 



body, in these punctures, and the larvae which hatch from the eggs feed 
upon the chrysalis, finally killing it about the time they become full- 
grown. They then leave the chrysalis and spin small, white cocoons, 
usually in a rather compact mass somewhere near what remains of their 
deserted host, emerging from these cocoons after a time, as adults which 





Fig. 366. — Pteromalus puparurn L., a (yhalcid parasite of the C'uljhage Worm and 
other insects: male (left), and female (right). Hair lines show the natural size. (Aflcr 
Chitlmden, U. S. D. A.) 

start another generation. It has been discovered that egg-laying in this 
species (and in many other parasites also) may continue during quite a 
long period provided the adult can obtain food, and this in many cases at 
least is accomplished by puncturing the body of the insect in which eggs 
are to be, or have just been laid, and feeding on its juices. 

Superfamily Serphoidea. — This superfamily, long known as the 
Proctotrypoidea, contains a large number of insects, nearly all very 




Fig. 367. — Pelecinus polyturator Dm.: a, female; h, male. Natural size. (Original.) 

small, and most of them parasitic on other insects or on spiders. Para- 
sitism of insect eggs seems to be very frequently the habit in the 
group. Some of the forms attacked by this group are Hemiptera, 
Diptera, Orthoptera, Lepidoptera, Neuroptera (Aphis lions) and Cole- 
optera, and some are found in ants' nests, parasitic on these insects. 
None of the members of the Superfamily is liable to attract the attention 
of those not entomologists, with one exception, an insect known as the 
Long-tailed Pelecinus {Pelecinus polyturator Drury), the female (Fig. 367a) 
pf which has along, slender body often between two and three inches long, 



352 APPLIED ENTOMOLOGY 

and glossy black in color. The extremely long abdomen of this insect 
which in flight is generally carried partly curled up beneath it, and its odd 
appearance also when at rest, sometimes cause it to be noticed and the 
remark made that it must be a dangerous animal. This is not the case, 
however, as the insect is harmless. It is a parasite on June bug larvae 
which it evidently seems to hunt for in the ground and it is particularly 
abundant in sandy localities. The writer has seen over 80 of these 
insects resting on fences, walls and elsewhere in the course of a single 
early morning walk in the streets of Nantucket, the distance covered 
being not over four city blocks. The male (Fig. 3676) which is extremely 
rare or at least seldom seen, has a short, club-shaped abdomen and is 
about an inch long. 



A general survey of the habits of the parasitic groups of the Hymenop- 
tera reveals several diversities of life and habits worthy of being presented 
together. In the first place all stages of the host may be subject to 
parasitic attack. The egg seems to be selected in some cases and the 
pupa or the adult in others: larvae however appear to be particularly 
liable to be parasitized. Where the egg stage is the one endangered, 
the parasite may consume its host before the latter can develop to the 
point where it is ready to hatch, thus preventing any injury whatever 
if the host be an injurious species. In other cases the host though para- 
sitized is able to complete its embryonic development, hatch, and feed 
for a time as a larva before it concedes victory to the parasite feeding 
within it and dies. In the case of larvae the parasitism may cause the 
death of the host before it becomes full-grown, or the latter may pupate, 
but progress no farther. Pupae parasitized are destroyed before becoming 
adult and adults attacked may or may not be able to live until they 
reproduce. 

These various relations of parasite and host have a bearing on 
the effectiveness of the parasite. In the majority of cases it is the 
next generation which is cut off, most of the injury normally caused 
by the host concerned being done before the parasite stops it, except 
in the case of the egg parasites which destroy the host before it hatches. 
Egg parasites of this kind therefore, are generally regarded as the most 
beneficial, though the great numbers of the other forms make their work 
very effective. 

Sometimes one parasite only, feeds upon its host. In other cases 
there may be many, as with some of the Ichneumonoidea, where in one 
instance over 1 ,200 were bred from a single caterpillar. It would seem 
that the parent parasite is able to calculate the amount of food furnished 
by a host and deposit only a sufficient number of eggs to correspond with 
the food supply. The more probable explanation, however, is that 



THE HYMENOPTERA 



353 



parasites laying many eggs regularly attack only those species of insects 
large enough to provide for the progeny, while those which lay only one 
egg in or on a host require all the food provided there for the single 
parasite. No case is known where a parasite normally laying many eggs 
in a host will select a smaller one and deposit only one or a few in it. 




Fig. 368. 



-Hawk-moth larva with cocoons of parasites which have fed upon it, on its back. 
{From Fell, N. Y. State Mus. Mem. 8.) 



Variations in the location of the pupa also occur. Some parasites 
pupate within the body of the host; others on its surface (Fig. 368) while 
still others leave the insect entirely, pupating singly or in groups, away 
from it. Tomato worms and other large caterpillars are often seen in 
the fall, either dead or dying, and with many small, white, oval bodies 
on their backs. These are cases where the numerous parasites after 
having completed feeding within the body of the host, have come out and 
pupated on its back, the white bodies being the cocoons of the parasites. 




Superfamily Chrysidoidea (The Cuckoo Wasps). — This is a rather 
small group of the Hymenoptera, the insects (Fig. 369) being seldom over 
half an inch in length and generally considerably 
smaller. Their bodies are green, of a metallic or 
bluish shade which quickly distinguishes them 
from certain of the bees which are also green 
but brighter. The surface of the body is gen- 
erally closely covered with fine indentations 
which give it a roughened appearance. 

These insects are able to sting but no poison 
gland seems to be present. The abdomen which 
has only a few (three to five) visible segments, is flat beneath, and 
when attacked the insect can roll itself into a ball for protection. 

The Chrysids are parasitic, chiefly on wasps and bees, though a 
few are claimed to attack saw-flies and one is a parasite on the Oriental 
Moth. The parent Chrysid watches its opportunity to visit the nest of 
its host and lays an egg in a cell with that of the host. On hatching, 

23 



Fig. 369. Cuckoo Wasp 
(Chrysididae)i somewhat 
enlarged. (From Bischoff.) 



354 



APPLIED ENTOMOLOGY 



the larva of the Cuckoo Wasp may eat the host or it may consume the 
food stored there,' thus starving the proper inmate of the cell. Adult 
bees and wasps know these enemies of their young and sometimes drive 
them away from their nests, though frequently without success, the Cuckoo 
Wasp watching its chance to return later unobserved. Taking into con- 
sideration the nature of the hosts of the Chrysids it is probable that as 
a whole the group should be considered inj urious rather than beneficial. 

Superfamily Sphecoidea (The Digger Wasps). — The insects of this 
group vary much in size, some being very small while others, particularly 
tropical species, may be more than an inch and a half long. Some of 
them are bright-colored, yellow, orange, green and black being the more 
usual colors, and the wings are frequently smoky and with an iridescent 
luster. A functional sting is present. 





Fig. 370. Fig. 371. 

Fig. 370. — Bcmbecid Wasp {Bemhidula quadrifnuciata Say), natural size. (Original.) 
Fig. 371. — Sphccid Wasp (Sceliphron ccevientarium Dru.), natural size. (Original.) 

Some of the insects (Fig. 370) in this superfamily (Families Bembecidse 
and Cerceridse) have the petiole connecting the mass of the abdomen 
with the propodeum very short, but in the others (Fig. 371) it is long and 
slender, the entire first segment behind the propodeum and sometimes 
a part of the second being very slender and elongate. These insects are 
often spoken of as the "thread-waisted wasps." 

The digger wasps are all solitary in their habits. The females of 
many species dig holes in the ground, in some cases several inches deep: 
others dig out the pith in plant stems: still others make nests of mud, 
gathered where there is moist earth, placing them under projecting 
stones, under eaves of buildings or in houses where access is easy through 
open doors or windows: in some species the nest is excavated in wood, 
and a few kinds have either not developed the nest-making habit or have 
lost it and use holes or the deserted nests of other species for themselves. 
In many instances the nest is subdivided into chambers separated from 
each other by partitions of mud. 

Wherever the nest, and whatever the material which composes it, 
its purpose is the protection of the young of the insect and of the food 



THE HYMENOPTERA 355 

which is stored there. After constructing the nest, either by digging, 
building, or otherwise, the parent starts out to provision it. The food 
differs with different species. Some take certain species of grasshoppers, 
others, flies: Homoptera, Hemiptera, Hymenoptera, Lepicloptera larvae, 
some Coleoptera, and Spiders, are also listed as the prey of digger wasps 
of various species. 

When one of the wasps finds an insect of the desired kind she attacks 
and stings it, generally not killing, but only partly paralyzing it and ap- 
parently chiefly the locomotor centers, so that it cannot escape. The 
prey is then grasped by the wasp and carried to the nest. In some cases 
flight is possible to the wasp carrying this load, but in many cases the 
prey is far too heavy for transfer in this way, at least in the case of those 
wasps which burrow in the earth, and it is therefore dragged along the 
ground to the nest. How the wasp knows the direction to take and 
how finally to locate the hole it is practically impossible to determine, 
but in most cases the insect seems to have little difficulty. 

Once arrived at the nest the prey is dragged into it and if it alone 
provides a sufficient food supply for the young wasp to be developed 
there, the parent now lays an egg on it and then closes up the opening 
of the nest. In the case of nests in the ground this is accomplished by 
scratching in dirt from around the hole and packing it in firmly. In 
three or four cases, species of the wasp genus Sphex have been seen by 
different observers to pick up a tiny pebble with their mandibles and, 
using it like a hammer, pound down more firmly the earth filled into the 
hole. This may perhaps be interpreted as representing the ''Stone 
Age" in the development of insects! 

If the single insect captured will not provide enough food for the 
young wasp, the parent proceeds to bring in more, until sufficient has 
been supplied, after which the opening is closed and another nest or 
cell, according to the kind of wasp concerned, is begun. In a few species 
the prey, instead of being paralyzed, appears to be killed and it is claimed 
that the wasp brings fresh supplies of food from day to day for the food 
of its young. 

Detailed studies on the lives and habits of these wasps have been 
recorded by many observers, and the remarkable traits these insects 
possess form one of the most interesting topics in Entomology. 

One species (Fig. 372) deserves particular attention because of its 
singular ways. It is a large wasp often called the Cicada-killer {Sphecius 
speciosus Drury) its body being over an inch long, its abdomen black with 
yellow marks. It is found over a large portion of the United States and 
appears during the dog-days in summer. It makes its nests in the ground 
and provisions them with adult dog-day cicadas (Homoptera), larger 
and heavier than itself, which it catches in the trees. The prey cannot 
be carried to the nest by flight but the wasp starts from the point of 



356 



APPLIED ENTOMOLOGY 




Fig. 372. — Cicada-killer {Sphecius spcciosus 
Dru.), about natural size. (Original.) 



capture with its paralyzed prey and flies as far as possible before striking 
ground. It has been claimed that at times the wasp drags the cicada 
up trees or bushes several times en route, in order to gain elevation for a 
fresh start toward its nest. The nests themselves may branch under- 
ground several times, each having 
a terminal chamber for the recep- 
tion of one or two cicadas and an 
egg of the wasp. 

Superfamihj Vespoidea (The 
Social Wasps). — This common 
name for the Superfamily is mis- 
leading, as a number of families 
included here do not live in colonies, 
but no other term at present ap- 
plied to the group is at all ex- 
pressive, and some at least of the 
insects included are colonial in 
their habits. 

Some of the Vespoids arc very 
small, being less than a sixth of an 
inch long, while others found in 
the tropics measure more than two inches, their bodies having a bright 
blue luster, and with orange or yellow wings. Forms present in the 
United States except in the South and Southwest are smaller, some 
having bodies marked with black and yellow. The families included 
in the group differ much in appearance and in habits, and it is probable 
that further study will result in the group being dismembered and 
several Superfamilies being formed instead of one. 

Some of the Vespoids are solitary, dig nests in the ground which 
they stock with spiders, and perhaps with some kinds of insects: others 
are parasites, some of the insects attacked being beetle larvae and cater- 
pillars, but in these a nest to which the prey is taken does not seem to be 
formed, an egg of the wasp being laid on its host wherever it is found, and 
the wasp larva, feeding there. Some appear to be parasites on bees and 
wasps, living in the cells of the bees and feeding on their young. Still 
others are not parasites but feed on honey, pollen, etc. 

In one family, known as the Velvet Ants or Stinging Ants (Mutillidae), 
many of the insects live in the nests of wasps and bees while others dig 
holes in the ground and store flies and other small insects there, it has 
been claimed. The males (Fig. 373) are winged, while the females (Fig. 
374) are wingless and very active. Both sexes are generally densely 
covered with hairs, often long, and generally of two or three contrasting 
colors, such as black with a red cross-band, or white, yellow and black. 
The females sting very effectively. Northern species are nearly all quite 



THE HYMENOPTERA 



357 



small but in the South are forms which are nearly an inch long and stout- 
bodied. 

In another family of this group one species known as the Tarantula- 
killer (Fig. 375) digs nests which it stores with tarantulas, the large hairy 





Fig. 373. Fig. 374. 

Fig. 373. — A male Mutillid {Traumatomutilla colorata Gerst). About twice natural 
size. {After Andre.) 

Fig. 374. — A female Mutillid {Ephuta occidentalis L.), slightly enlarged. {After 
Andre.) 

spiders of the South and Southwest where this insect is found. It is a 
large and powerful wasp, about two inches long, but in its battles with 
the tarantula it is not always the victor. 






Fig. 375. — Tarantula-killer (Pepsis marginata Fab.), somewhat reduced. (Original.) 



The insects of the family Eumenidse are very abundant in this 
country. Most of them are rather small (Fig. 376), and black with yellow 
markings seems to be the favorite color combination, as so frequently is 
the case with the other groups of wasps. Some make burrows in the 



358 



APPLIED ENTOMOLOGY 



ground; others tunnel in wood and divide the tunnel into cells by cross 
partitions of mud ; while others build cells of mud. some kinds of which, 
attached to twigs are like jugs or urns (Fig. 377) in form, with an upper 
flaring lip which, after the nest has been stocked with food for their young, 
is sealed with mud. The mud workers of this 
family are often called the Mason-wasps. All 
the wasps of this group are predaceous. 

In the family Vespidse we come to the social 
wasps, living in colonies, and with three types of 
members, the males, females and workers, these 





Fig. 370. Fig. 377. 

Fig. 376. — Eunienid Wasp (Eumenes fraternus Say), natural size. (Original.) 
Fig. 377. — Two nests oi Eumenes fraternus, natural size. {Original.) 

last being females in which the reproductive organs have undergone 
little or no development and the insects themselves are smaller than the 
true females. 

The colonial life of these insects continues only during the summer, 
all but the females dying as winter approaches. In the spring the 





Fig. 378, Fig. 379. 

Fig. 378. — Social Wasp (Polistets pallipe!< Lep.), about natural size. (Original.) 
Fig. 379.- — Nest of Polistes pallipes, as found before the colony has increased much 
in numbers. Reduced slightly. (Original.) 



female (Fig. 378) starts a colony, first building a cluster of six-sided cells 
which are in some cases attached to the under side of some projecting 
rock, eaves, or in a similar position (Polistes). These cells (Fig. 379) are 
made from weathered wood, chewed up by the insect into a sort of gray 



THE HYMEN OPT ERA 



359 



The adults which 



paper pulp and then molded into the desired form. In these cells she 

now places eggs and the young which hatch are fed upon insects partly 

chewed up, with perhaps the addition of some pollen. The young feed 

upon this until full-grown, then pupate in their cells. 

emerge are workers and they now begin to 

construct additional cells all in the same 

layer; feed the young and do the other work 

of the colony. Later in the season males and 

females are also produced and mate. Late 

fall stops further growth of the colony and all 

but the females die. 

Other insects of this family (Vespida, Fig. 
380) use wood partially decayed, with which 
to construct their nests, and an outside wrap- 
ping is added. Here one layer of cells will not accommodate the colony 
and several layers or tiers of cells surrounded by these wrappings are pro- 
duced, leaving only one or two exit openings. Sometimes these nests are 
placed in holes in the ground and the wasps locating in such places are 




Fig. 3S0. — Social Wasp 
{Vespula vulgaris Fab.), about 
natural size. (Original.) 




Fig. 381. 



-Nest of a Hornet {Vespula maculala Kirby.), about one-eighth natural size. 
(Original.) 



often called "yellow-jackets." Other species construct their nests in 
trees or bushes (Fig. 381), attaching them to a branch or branches. 
There are several outside wrappings of gray papery wood pulp surround- 
ing the tiers of cells within, of which there may be three or four, and the 
exit opening is usually at or near the bottom of the nest. Insects making 
nests of this kind in trees or under eaves, gable-ends of buildings or 



360 APPLIED ENTOMOLOGY 

similar places, are generally called hornets, though there is really no 
sharp distinction between them and yellow-jackets, in the usual use of 
these names. The life of the colony in the case of these insects does not 
differ from that of the forms described above which make only one 
layer of cells with no outside wrappings (Polistes), but in the yellow- 
jackets and hornets the colony increases much more rapidly and by fall 
may number several hundred individuals. 

Taking the wasps as a whole, we find an interesting progressive 
development in the different groups. As regards their habitations, we 
may perhaps regard the holes dug in the ground as being the simplest, 
followed by excavations of the pith of woody stems, the construction 
of mud nests and finally along this line the formation of artistically 
shaped' urns, as progressive steps in architectural ability. The con- 
struction of hexagonal cells of paper pulp, first in a single layer, then in 
several layers surrounded by a paper wrapping and finally much more 
substantially built to resist exposure to the weather above ground may 
be regarded as continued progress in this line, the nest of the hornet 
marking the climax of the series. 

Somewhat parallel to this is the nature of the food. The nests 
in the ground, in plant stems, and in mud cells, are provisioned with 
insects stored as food for the young of the forms constructing them: 
in other words these wasps are parasitic insects. With the appearance of 
cells of paper pulp the food changes to a mixture of insects killed and 
partly chewed up, and of plant materials such as pollen. At this same 
point also, a change from a solitary to a colonipJ life begins and as the 
colony becomes larger the nest increases in size and strength. 

There is therefore a progressive development in the insects of these 
Superfamilies, illustrated in nest structure, food, and the advance from 
solitary life to that of a large colony. 

Superfamily Apoidea (The Bees). — The bees familiar to everybody, 
are the bumblebees and the honey bee, but these form a very small part 
of the insects belonging in this superfamily. Many of the bees are 
solitary in their habits; are rather small insects and little attention 
is paid to them. They are important insects, however, valuable to man 
as they visit flowers and cross pollinate the blossoms. 

The bees have the first segment of the hind tarsus somewhat enlarged 
and flattened, and in those which carry pollen there, hairs are present 
to aid in this. In addition, the hairs on the thorax are branched or 
plumose while in the other Hymenoptera they are simple. 

Some of the bees are solitary (Fig. 382) and dig holes in the ground, 
generally with side pockets in which pollen or pollen and honey are 




THE HYMENOPTERA 361 

placed as food for the young. An egg is then laid in each pocket. 
Others lay their eggs in the nests of other bees and are parasites upon 
them, or inquilines in some cases, consuming the food provided for the 
rightful inhabitant and starving it. Some construct mud nests while 
others cut off pieces of leaves or sometimes flower petals, with which 
they line cavities they excavate in wood, for their nests, and still others 
tunnel in wood but use no leafy lining. The colonial forms establish 
their homes in various places and build combs of wax in which to store 
the pollen and nectar which is their food and that of their young. 

Though many of the bees are solitary there is in some species a 
tendency to make their holes in groups forming what are frequently 
called "bee villages." In a number of species this goes 
still further, several bees uniting in the excavation of 
a central burrow but each making lateral passages 
from this to cells which are her own and in which her 
own young are produced. If the former could fairly be 
called "villages" it would seem that these last could 
with equal propriety be described as "apartment Fig. 382. — Soli- 
houses," as has been done. Some of the bee villages ^^J^ Bee, some- 
will include several thousand nests within a few square (Original.) 
feet and might even be termed "bee cities." 

Some bees have a rather short hinder lip and are known as the "short- 
tongued bees," but in the majority of these insects the central portion is 
long and slender, enabling such forms to reach the nectar in long-tubed 
flowers that would otherwise be inaccessible to them. 

The leaf-cutter bees are usually rather small. Their nests are not 
often noticed, being made in holes (frequently in wood) sometimes 
dug by the bees themselves, but the leaves which they cut are familiar 
objects as the cut is frequently a very true circle or double circle, the 
piece removed in the latter case being rather oblong with rounded ends. 

The large Carpenter Bees (Xylocopa) are about the size of bumble 
bees but in most cases are easily distinguished from them b^ the smooth 
and glossy upper surface of the abdomen. These insects tunnel in 
wood, often to quite a distance. The tunnels are divided into cells by 
partitions of wood chips, a partition being built across after each cell 
has been provided with a mixture of pollen and nectar and an egg. 

Bumblebees {Bo7nbus, etc., of many species). — There are many kinds 
of bumblebees widely distributed over the globe but none are found native 
in Australia. They live in colonies during the summer but only the queens 
(females) survive the winter. In spring the queen (Fig. 383) seeks some 
suitable place for a nest, generally a hole in the ground, and frequently 
the deserted nest of a field mouse is chosen for the purpose. Here she 
places a mass of pollen on which she lays some eggs, and the larvae which 
hatch, feed upon the pollen, and when full-grown pupate in silken cocoons 




362 APPLIED ENTOMOLOGY 

from which workers emerge. These are undeveloped females, smaller 
than the queen, and they now take up the work of the colony, strengthen- 
ing the cocoons with wax and using them to store honey in. The colony 
increases in numbers and late in the season males (drones) and females 
(queens) are also produced and live together until the approach of cold 
weather, when all but the young queens die, these going to protected places 
to pass the winter. 

The value of the bumblebees to man is apparently based upon the 
fact that in these insects the middle part of the hinder lip (tongue) 
is longer than in most of the other bees, and that therefore they visit and 

cross pollenize flowers having a 
nectary so long that the nectar in it, 
from which honey is made, cannot 
be reached by the other species, 
which accordingly do not visit such 
flowers. One such plant is the com- 
mon red clover which in the United 
States is enabled to produce seed, 
chiefly as a result of the visits of 
Fig. 383.— Queen Bumblebee {Bom- bumblebees, which makes these 

bus pennsyhanicus Dc G.), natural size, j^sects important aids tO those who 
(Onginal.) ^ 

raise clover seed. 

Insects so closely resembling bumblebees that it has incorrectly 
been said that the latter cannot distinguish them from themselves, are 
often found in bumble bee nests, living there as inquilines. The females 
of these inquilines (genus Psithyrus) however, have no structures on 
their hind tarsi for carrying pollen. In these inquilines there is no worker 
caste. The eggs are laid in the bumblebee cells and on hatching the 
young are fed by the bumblebee workers like their own, and the adults 
go in and out of the nest without molestation. Whether they have some 
function beneficial to the insects with which they live and which provide 
for them is as yet unknown. 

The Honey Bee (Apis mellifera L. ). — There are a number of species 
of honey bees in different parts of the world, but in the United States 
our knowledge and experience with these insects is limited to the above 
named kind, often called also, the Hive Bee. 

This insect is a native of Europe but was introduced into America 
centuries ago. In many instances, colonies have escaped from domesti- 
cation and wild honey bees are abundant as a result. There are several 
races of the Honey Bee, the most common one, at least wild, being the 
Black or German bee, as this was the first race to be brought to this 
country. The German bee has a black abdomen; is not a particularly 
good honey producer and has a decidedly bad temper, besitdes being less 
able to protect itself from some of the insects such as the bee moth, which 



THE HYMENOPTERA 



363 



live in its nests, than are some of the other races. The Italian bee is a sHghtly 
larger insect with dullyellow stripes on its abdomen; an excellent honey 
producer, gentle in disposition; can protect itself quite well from other 
insects, and at the present time is the most popular race in this country. 
Other races more or less frequently met with are the Carniolan having a 
gray abdomen, the Cyprian with a yellow abdomen and a very bad tem- 
per, and the Caucasian with a yellow-gray abdomen. Interbreeds of the 
black and Italian bees are very common and have more black on the 
abdomen than the pure-bred Italians. 




Fig. 3S4. — Honoy Bpp (Apis vicUifcra L.): a, drone; h, (iiieoii; r. workor. Ahoiit nntunil 

.size. (OriijinaL) 

A honey bee colony consists of a queen or fully developed female; 
workers which are partly developed females; and drones or males during 
a part of the year (Fig. 384). The queen lays eggs in the cells and the 
young are cared for by the workers which also gather food for themselves 
and the young bees, make the comb, put the nest in good condition and 
keep it so, and in fact do all the work necessary for the colony. The 
drones exist solely to fertilize the queens, taking no part in the work of the 
colony, and feeding on the stores brought in. On the first tarsal segment 
of the hind leg in the workers is the " pollen basket," a flattened or slightly 
hollowed oval surface surrounded by a fringe of long hairs. 

An ordinary colony in good condition will consist of several thousand 
bees, the number at any time varying and determined by the rapidity of 
the production of young, the departure of many by swarming, and other 
factors. Swarms containing over fifty thousand bees have been seen, 
and the colony they left behind also contained at least a few thousand. 

A laying queen bee has a body about three quarters of an inch long: 
the drone has a shorter but stouter abdomen, and the workers are about 
half an inch long. 

The life of the queen may be several years. Ordinarily, workers live 
only a month or two, but those produced in the fall live over winter and 
far enough into the spring to care for the young produced at that time. 
Drones live only a few months and are killed by the workers when their 
usefulness is ended. 

The life of the honey bee has been modified in many ways by its 
relation to man. Under natural conditions where no human interference 



364 APPLIED ENTOMOLOGY 

occurs, the following may be regarded as an outline of the life of a bee 
colony. 

Starting with a "swarm," which consists of a laying queen and a 
mass of workers, which has left its former home, this swarm flies to a new 
place in which to establish itself, such as a hollow tree. Here the workers 
clean out the cavity, removing loose particles of wood and such other 
debris as can be carried out. All cracks and openings to the exterior 
except one or two, are then stopped up with Propolis, a dark-colored, 
sticky material which the bees gather from the buds of trees, particularly 
poplars where these trees occur, and carry to the nest in their pollen 
baskets. 

The production of wax with which to make cells in which food is 
stored and the brood raised, is next in order. To obtain this, some of 
the workers feed freely and hang upon the walls of the nest but do no 
work. Soon tiny scales of wax appear on the under side of the abdomens 
of these workers, produced by wax glands along the inner side of the chi- 
tinous wall of the body there, and poured out through openings leading 
from these glands to the surface. This wax is gathered, worked over and 
molded into the form of sheets of "comb," attached at their tops to 
some part of the hive and hanging downward. Generally these sheets 
are more or less parallel to each other and with only a narrow space left 
between them when their construction has been completed. 

Each sheet of comb consists of two layers of cells back to back, each 
cell being six-sided. The long axis of the cell is nearly at right angles to 
the plane of the sheet of comb as a whole, but tipped slightly upward. 
Comparing cells on the two sides of the comb it is seen that a cell of one 
side backs against parts of three of the opposite side, and that the parti- 
tion at the inner end of each cell slopes so that the center is its deepest 
point. Mathematical study of the construction of the cells shows that 
by this form and arrangement of the cells the greatest amount of storage 
space is obtained with the least expenditure of wax, of any form which the 
bees could use. In some of these cells, usually those around the top and 
sides of the comb, food is stored, while the central and lower portions 
are used for the production of the young. 

As soon as comb is available the storing of food and the production of 
young begin. The workers go out and visit flowers, gathering the pollen 
in their pollen baskets and bringing it to the nest where it is stored in 
cells. They also collect nectar from the blossoms, carrying it to the nest 
in the honey sac, an enlargement of the oesophagus just in front of the 
stomach (Fig 24, hs). On reaching the nest this nectar is expelled into a 
cell and the cells selected for this purpose are gradually filled. From time 
to time workers visit these cells and draw the nectar from them into their 
honey sacs, then driving it back into the cell again and repeating the 
process, which removes water from it and concentrates it into honey. 



THE HYMENOPTERA 365 

The queen lays her eggs on the bottoms of the cells selected for the 
raising of brood, one egg in the bottom of each cell. The eggs hatch into 
stout, white, maggot-like larvae (Fig. 385) which are fed by the worker 
bees with a material generally called "bee bread" which appears to be 
pollen mixed with some honey. When the larvse are full-grown and ready 
to pupate the workers cap over with wax the openings of the cells occu- 
pied by such larvae and these proceed to pupate (Fig. 385). After the 
changes undergone during pupation have been completed the adult thus 
produced bites away the cap closing the cell it is in and emerges as the 
adult. 



OTZ 




Fig. 385. — Section of comb of Honey Bee: FL, feeding larva in the bottom of its cell; 
SL, larva ready to pupate, spinning its cocoon; N, pupa; an, antenna; cc, compound eye; 
CO, cocoon; e, excrement; ex, exuvium; m, mandible; sp, spiracle; t, tongue; iv, wing. {After 
Cheshire.) 

In the case of eggs which are to become drones (males) the cells in 
which such eggs are laid are apparently of a slightly greater diameter than 
those where workers are to be produced, though this is denied by some 
students of the subject, and they are longer, projecting out beyond the 
line of the general surface of the brood cells, at least after being capped, so 
that they are easily recognized. 

The queen is fertilized but once, at which time the sperms of the drone 
are stored in the seminal receptacle of the queen. She lays both fertilized 
and unfertilized eggs, the latter producing the drones. By the Dzierzon 
theory, whether the egg is to be fertilized or not depends upon the will of 
the queen. If the cell in which the egg is to be laid is a worker cell, at the 
moment the egg passes down the oviduct by the opening of the seminal 
receptacle the muscles surrounding the receptacle are slightly contracted 
and sperms are expelled, one of which fertilizes the egg, while if the egg 
is deposited in a drone cell the muscles are not contracted and the egg is 
unfertilized and produces a drone. While this is the more generally 
accepted theory, the alternative view is held by some persons that the 
smaller diameter of the worker cell produces pressure on the abdomen 
of the queen which forces some of the sperms out, and that in case of 
drone cells their greater diameter prevents this. 

Queens are produced only during the late spring and summer months 
when swarming is desired. At such times the workers select a cell already 



366 APPLIED ENTOMOLOGY 

containing a worker egg and tear down those around it and construct a new 
cell about the shape and size of a small peanut, to enclose the egg, and with 
its opening usually facing downward. When the egg in this cell hatches 
the larva is fed on "royal jelly" which is probably bee bread mixed with 
an albuminous secretion derived from glands situated in the heads of the 
workers, and which is richer and more nutritious than bee bread. With 
this richer food and a larger space in which to develop, the workers are 
thus able to produce a queen from a worker egg. There are often a num- 
ber of queen cells of different ages in a nest at once. 

The time required to produce a queen from egg to adult is about 153^^ 
days: for a worker, 21 days; and for a drone 24 days. 

Swarming is for the double purpose of relieving colonies whose nests 
would otherwise become over-crowded, and for the establishment of 
new ones. Though many of the details of this process may vary on 
different occasions, the usual story of swarming is about as follows. 

When the colony is in such a condition during late spring or summer 
that swarming will soon be desirable, drone cells and queen cells are con- 
structed and after a time the first of the new queens completes pupation 
and begins to bite off the wax cap over the mouth of her cell. At this 
time she makes a peculiar noise cofnmonly called a "piping" sound, and 
when the old queen hears this she becomes greatly disturbed and begins 
to hunt for the young queen to sting and kill her before she can escape 
from her cell, if possible. If a swarm just at that time is not desired by 
the workers for any reason, she may be allowed to do this, but if swarm- 
ing is to take place workers cluster so thickly over and around the young 
queen cell that the old queen cannot reach it. This opposition to her 
wishes, passive though it is, or the knowledge that another queen will 
quickly be present in the colony seems to arouse and excite the old queen 
greatly and this excitement spreads to the workers, particularly the 
younger ones. Scouts now go out to find a home for the swarm and 
finally the old queen and a mass of workers leave the hive together. In 
some cases they go directly to their new home, but most often they fly 
only a short distance before clustering on the limb of some bush or tree 
for a time before flying to the new nest. Once arrived there, the work of 
preparing the place, stopping the cracks and the production of comb 
begins, as already described. 

That part of the colony remaining behind now consists of workers, 
drones and a young, unfertilized queen. The queen on escaping from 
her cell usually explores the brood cells and if she finds other queens 
developing she stings them in their cells to assure her supremacy, unless 
prevented by the workers. A few days later the queen leaves the nest on 
a pleasant day for a flight during which she mates, after which she returns 
to take up her duties as queen of the colony. 

Several possibilities may become realities in connection with swarm- 



THE HYMENOPTERA 367 

ing. One of these is the chance that two young queens may emerge 
at almost the same time. If this should happen it is stated that the 
two meet sooner or later and struggle for supremacy until one or the 
other is killed. A second possibility is that both of the queens may 
be so injured that they will die, or as probably is more often the case, 
the queen while out on her mating flight may be killed by a bird or in 
some other way. In either case the colony becomes queenless as a result. 
If other queen cells are present in such cases, the workers carry on the 
work of the hive until the new queen appears, mates and takes charge: 
but if there are no more queen cells the workers look about for a worker 
egg or a larva not more than 3 days old. If one is found, its cell walls 
are torn down and a queen cell built around it and its food is changed 
from bee bread to royal jelly and in this way a queen will be produced. 
If an egg or a worker larva under this age cannot be foimd, however, the 
colony cannot hope to obtain a queen and it gradually dwindles away and 
is lost. 

Drones, serviceable to the colony during the swarming season, are 
not needed thereafter and would consume stores gathered for winter. 
Therefore after all swarming is over they are dragged Dut and killed 
by the workers. 

The value of the honey bee to man comes from the honey and wax 
it produces. The amount obtained varies greatly from year to year 
but averages over fifty million pounds a season in the United States 
and at a recent average retail price of forty cents, would represent about 
twenty million dollars. This is probably more though, than is actually 
received by the beekeepers. About a million pounds of wax are now 
l)roduced annually and at about forty cents per pound this would add 
nearly half a million dollars more to the value of the industry in this 
country. 

Superfamily Formicoidea (The Ants). — These familiar and plentiful 
insects occur from the frigid regions to the equator, being present in 
abundance practically everywhere, and it has been claimed that there 
are more individuals of ants than of all other terrestrial animals. They 
live in colonies which are quite permanent, enduring for many years in 
some cases, and the life of an individual ant may continue for several 
years. 

Ants are nearly always easily recognized by the presence of a petiole 
which is enlarged near or behind its middle (Fig. 38Qe), being either 
swollen or having a portion projecting upward there, followed behind 
by a constriction where this segment joins the rest of the abdomen. 
In some ants the following segment is also more or less similarly shaped. 
This gives these insects a rather elongate, narrow portion between the 
thoracic and abdominal masses, enlarged at one or two places, according 
to the number of segments concerned. 



368 



APPLIED ENTOMOLOGY 



Three classes of ants always compose a colony — males, queens 
(females) and workers — and there may be subdivisions of each of these 
in some cases. The males and females usually have wings during a 
portion of their lives, these having a simple arrangement of the veins: 
the workers are wingless though some have vestiges of these structures. 
The queens and workers are provided with a well-developed sting in some 
groups of ants, while in others it is vestigial or entirely absent. The 
usual colors of ants are yellow, brown, black, red, dull red, or brownish 
yellow. 




Fig. 386. — Little Black Ant {Moiiomorium minimum Em.): a, male; h, pupa; c, female; 
d, winged female; e, worker;/, larva; g, eggs; workers in line of march below. All enlarged, 
hair lines showing true length. {From U. S. D. A. Farm. Bull. 740.) 

Colonies of ants occur in many kinds of locations. Some are in 
the ground and these may be of different types of structure; some occur 
in the cavities of plants, either preformed or else tunneled out by the ants: 
some form nests on branches, making them of various materials; and 
some nest in timbers, or other unusual places, while a few kinds have no 
fixed homes. 

The food of ants is as varied as are their nest locations. Probably 
the original food of the group was insects, either dead or helpless, and 
many species feed on this material. Others take the honey-dew supplied 
by scale insects, leafhoppers and particularly by plant-lice. Some raid 



THE HYMENOPTERA 369 

the nests of other species of ants and feed on their larvse and pupge. 
Plant seeds, bulbs, and the bark on tender roots also form the food of 
some ants, and one tribe raises a fungus in order to feed upon its hyphse. 
Sweet materials such as cake, candy, sugar, molasses, etc., in houses, 
often attract ants, which find in these substances satisfactory foods. 

Colonies in the ground may vary from those having a single tiny 
entrance and a few tunnels and galleries below the surface, to large 
ant hills several yards in diameter and several feet high, with extensive 
galleries both above and below the general ground leveK Fig. 388). In 
these nests may be found a queen (frequently several) ; males, at least at 
times; and often many thousands of workers. The queen or queens 
produce the eggs which are carried away and cared for by the workers, 
who also feed the larvae, clean them, transfer them from one part of 
the nest to another, according to the temperature and other conditions 
they need, and finally aid them in escaping from their cocoons. They 
also feed the queen and do all the work of the colony. 

The eggs laid may develop either into males or females and workers, 
and Dzierzon's theory given above for bees has been applied to ants also, 
though some evidence that unfertilized eggs may in certain cases produce 
workers tends to throw doubt on the applicability of this theory to ants. 

At certain seasons of the year swarming occurs. At such a time 
enormous numbers of winged males and females, previously produced in 
the nest, leave it and take flight. Mating occurs in the air and the 
females soon return to the ground where they remove their now useless 
wings, either by pulling them off with their legs or jaws, or by rubbing 
them against the ground, stones or grass-stems. The queen now prepares 
a nest by digging a hole in the ground, in rotten wood or elsewhere, 
forming a small chamber at the inner end and closing the entrance. 

"In her cloistered seclusion the queen now passes days, weeks, or even 
months, waiting for the eggs to mature in her ovaries. When these eggs have 
reached their full volume at the expense of her fat-body and degenerating wing- 
muscles, they are laid, after having been fertilized with a few of the many thou- 
sand spermatozoa stored up in the spermatheca during the nuptial flight. The 
queen nurses them in a little packet till they hatch as minute larva^. These she 
feeds with a sahvary secretion derived by metabolism from the same source as 
the eggs, namely, from her fat-body and wing-muscles. The larvae grow slowly, 
pupate prematurely and hatch as unusually small but otherwise normal workers. 
In some species it takes fully 10 months to bring such a brood of minim workers 
to maturity, and during all this time the queen takes no nourishment, but 
merely draws on her reserve tissues. As soon as the workers mature, they break 
through the soil and thereby make an entrance to the nest and establish a com- 
munication with the outside world. They enlarge the original chamber and con- 
tinue the excavation in the form of galleries. They go forth in search of food 
and share it with their exhausted mother, who now exhibits a further and final 
change in her behavior. She becomes so exceedingly timid and sensitive to 

24 



370 APPLIED ENTOMOLOGY 

light that she hastens to conceal herself on the slightest disturbance to the nest. 
She soon becomes utterly indifferent to her progeny, leaving them entirely to 
the care of the workers, while she limits her activities to laying eggs and imbibing 
liquid food from the tongues of her attendants. This copious nourishment 
restores her depleted fat-body, but her disappearing wing-muscles have left her 
thoracic cavity hollow and filled with air which causes her to float when placed 
in water. With this circumscribed activity, she lives on, sometimes to an age of 
15 years, as a mere egg-laying machine" (Wheeler). 

Of course there are many fatalities in such a history as this. Birds, 
dryness in their, burrows, excessive moisture or cold, underground insects 
attacking them, together destroy the great majority of these ants just 
starting new colonies. Then too, the amount of nourishment stored in 
the individual is an important factor, some species having so little that 
they are wholly unable to start new colonies. An individual of such a 
species therefore either joins a colony already established, a queenless 
colony of a related species if she can induce the colony to accept her, or 
she may enter a colony of a very different species and, killing its members, 
raise their young until they emerge when they will accept her as their 
queen. Rarely two queens may start a colony together. 

After the colony is well under way the queen limits her duties to egg 
laying, and may live many years. In one case a queen lived nearly 
15 years in confinement and may have been older! This is the greatest 
age known to have been attained by any adult insect. The males die 
soon after mating. 

The relation of ants to plant lice is most interesting and has already 
been referred to (pp. 197 and 203). It does not exist with all species 
of ants but in at least a large number honey-dew is an important part 
of their diet and in some cases it may be their only food. There is every 
evidence that the benefit is mutual, the ants protecting the aphids, driv- 
ing away the enemies of these insects or carrying the aphida to protected 
places. Ants that care for root-feeding aphids keep them in chambers or 
galleries, conduct them to their sources of food supply, collect and store 
their eggs for the winter, and in spring take the young to their food. 

The Corn-root Aphis so injurious to corn, as already described, is 
thus cared for by ants. Scale insects which produce honey-dew are also 
cared for in a sense, for ants are very attentive to them and to quite an 
extent prevent the attacks of the enemies of the scales by their presence 
and activities. Thus in an indirect way the protection by ants of 
plant lice, scale insects, white flies, leaf hoppers, and in fact any insects 
which produce honey-dew, establishes such ants as injurious. 

Some kinds of ants have most remarkable habits worthy of a brief 
reference here. Some species may make raids on the nests of other 
kinds, and carry off their worker larvae and pupae to their own nests, 
where many probably serve as food but a few may be reared and become 



THE HYMENOPTERA 371 

slaves. Slavery is not essential with all the kinds of ants where it is 
known, colonies having no slaves being able to carry on their lives unaided 
by slaves. With certain species, however, the situation is different. 
In these the workers have mandibles so constructed that they are unable 
to gather food, excavate their nests or care for the young. Accordingly 
they make forays on the nests of other species, bringing back larva? and 
pupae which on becoming adult are slaves which do the work of the colony 
and care for their captors, both as adults and during their early stages. 

The honey ants, so-called, include those species in which the crop is 
capable of great distention, and this power is made use of by collecting 
honey-dew and storing it until the abdominal mass is enormously dis- 
tended and (in some species) about the size of a large currant, such in- 
dividuals becoming animated food reservoirs. These members of the 
colony hang on the ceilings of their galleries, withdrawing from the 
regular duties of the other workers. The reason for the existence of 
such a peculiar habit is suggested by the fact that the honey ants are 
confined to dry plains and desert regions, being found in North America, 
South Africa and Australia. They are therefore probably true reservoirs 
of nourishment which may be drawn upon during periods of drought, 
when the ants must remain for some considerable time in their nests. 

Some ants raise fungi upon which to feed, about one hundred kinds 
which do this being known. These insects in most cases go in large num- 
bers to trees and some climb the trees and cut off the leaves while other 
members of the colony pick these up from the ground where they have 
fallen and carry them to their nests where the fungus is grown on them. 

A few species of ants are obnoxious to man, either by invading houses, 
making their nests in lawns or in trees, or by to some extent protecting 
injurious insects. 

The Argentine Ant {Iridomyrmex humilis Mayr.) is a native of 
South America which probably reached this country between 1880 and 
1890 at New Orleans and now is present nearly everywhere in most of the 
southern tier of states, and in California as far north as San Francisco. 

The adults (Fig. 387) are brown in color. The queens are about a 
quarter of an inch long, the males about half that length, and the workers 
about a tenth of an inch long. Their summer nests " may be located 
anywhere — under sidewalks, under the sills of houses, in brick piles, stone 
piles, under a piece of board or a piece of tin, in an old tin can — in fact, 
in any place convenient to the food supply. In the winter months there 
is a tendency to concentrate into larger colonies, and they seek warm, 
dry, secure nesting places in which to hibernate" (E. R. Barber). 

Egg production is probably quite large — perhaps 50 or more per day 
under favorable conditions — and an average of 40 days in warm weather 
is required for development from the laying of an egg to the emergence 
of the adult worker. 



372 



APPLIED ENTOMOLOGY 



This is one of the worst of house pests known in the regions where it is 
abundant. Its small size enables it to enter through the smallest cracks 
and it goes everywhere in houses after its food. It will eat practically 
everything in the way of foods, both raw and cooked, and no part of a 
house is free from its presence. The cold of ice chests does not repel 
them and beds are not entirely protected by placing the bedposts in dishes 




Fig. 387. — Argentina Ant {Iridomyrmsx humilis Mayr.) : 1, wingless female; 2, worker, 
3, early stages: a. eggs; 6, young larva; c, full-grown larva; d, side view of pupa; e, ventral 
side of pupa; /, dorsal view of pupa, 4, male. All greatly enlarged. {From U. S. D. A. 
Farm. Bull. 740.) 



of water or kerosene, as after a few hours a film of dust forms on the 
surface of this, over which with their light bodies they are sometimes able 
to pass. Though they do not sting, they bite freely and are able to 
cause some pain in this way. Young children asleep have been found 
with ants in the nose, ears and mouth, and 'older persons are frequently 
inconvenienced by them in a similar way. They visit plant lice, soft 
scales and other insects for honey-dew and to some extent at least, then- 
presence is favorable to these pests and makes their control more difficult. 



THE HYMENOPTERA 373 

Control. — Heavy rains, causing a flooding of the nests is a natural means 
of checking the ravages of these insects, many being killed, particularly 
in cold weather. Barriers on the legs of tables, beds, etc., consisting of 
tape, soaked in a saturated solution of corrosive sublimate (Hg CI2), 
dried, and then fastened around such places will keep the ants away for 
several months at least. A generous supply of naphthaline in the form 
of moth balls, placed in a dish in which a leg of a piece of furniture rests is 
also effective, provided each leg is thus treated. Kerosene instead of moth 
balls, as already described, is generally of some value as a protection. 

Various ant poisons have been tested, and a syrup of granulated 
sugar, water, tartaric acid, sodium arsenite and honey has been found 
to be very effective, and it also keeps well. Placed in a tight tin with 
two sides dented in and with a tin cover, the ants can enter and feed 
while the syrup remains protected from the weather. A gill or two of 
syrup and a fairly large piece of sponge floating in it will complete the 
trap for use. Traps should be placed both in and around the house, of 
course out of the reach of children, and by adding a bail or handle can 
be hung on walls, the branches of trees and in similar situations. Eight 
or ten of these are sufficient for an ordinary city house and lot and will 
be effective at least for 6 or 8 weeks. 

House Ants.— These are of several kinds but the one most usually 
troublesome is the Little Red Ant (Monomorium pharaonis L.), probably 
a native of Europe but now abundant in nearly all countries. It is very 
small, red in color, and makes its nests in walls, floors, sills or other 
timbers, whence it explores all parts of the houses, paying particular 
attention to those places where food is found. Oftentimes regular lines 
of these pests may be found marching from some article of food they 
have discovered to their nest, and another line beside the first, on their 
way to obtain food. In such cases it is sometimes easy to trace their 
line of march back to where they enter some timber in which their nest 
is placed, and then the injection into the holes where they enter, 
of carbon disulfid or benzine may prove sufficient to kill the queen 
or queens and terminate the life of the colony. In too many cases 
though, it is impossible to locate, or perhaps to reach the nest. Where 
this is true it has been found that small pieces of sponge, soaked in mo- 
lasses and water, and a little arsenic, placed where ants are will generally 
attract the pests, which will feed upon the poisoned syrup and be killed. 
In this way the number of individuals is frequently reduced more rapidly 
than the colony increases and the ants gradually become less abundant 
and finally disappear. Simple protection of food or other materials can 
usually be obtained by placing around such articles a continuous, liberal 
band of powdered cloves. 

Where ants are nesting in living trees they usually enter where some 
limb has been lost, and their entrance holes in the wood can be found. 



374 



APPLIED ENTOMOLOGY 



Pouring carbon disulfid or benzine into these and then stopping the 
holes with putty or mud is in most cases, sufficient to kill the queen, and 
in consequence, the colony. 

Ants in lawns or elsewhere may make mounds (Fig. 388) or may 
simply loosen the soil and more or less injure the grass at such places. 
To destroy such nests a stick, such as a cane or a broom handle, should be 
driven down to the bottom of the nest, at which point the loosened earth 
ends and driving becomes hard. These holes should be about a foot 











Fig. 388. — Ant hills. (From a photograph by H. B. Peirson.) 



apart and enough of them be made to cover the entire surface of the nest 
at this distance. Into each hole a tablespoonful or two of carbon di- 
sulfid is now poured and each opening closed at the top, which is suffi- 
ciently done by pressing the earth together at each hole with the foot. 
The carbon disulfid gas penetrating through the underground galleries 
of the ants will kill them, including the queen, and the colony will 
disappear. 

This treatment should be applied on a warm, dry day, to hasten the 
change of the liquid to the gas and its rapid dissemination through all 
parts of the nest. 



INDEX 



Abdomen, 14 

Abdominal feet, 14, 232, 252, 272, 300 

Acrididse, 81-85 

Aculeata, 339 

Adalia bipunctata, 133 

Aedes segypti, 309 

sollicitans, 307 
^geriida?, 243-246 
Agamic reproduction, 154, 196 
Agglomerate eyes, 9 
Air tubes, 18 
Alabama argillacea, 269 
Alaus oculatus, 108 
Aleyrodes vaporariorum, 207 
Aleyrodidae, 187, 206-208 
Alfalfa caterpillar, 295 

weevil, 143 

worm, 274 
Alsophila pometaria, 253 
Amblychila cylindriformis, 101 
Ambrosia beetles, 146 
Ambush-bugs, 182 
American roach, 78 
Ametabola, 25 

development of, 26 
Anabrus purpurascens, 87 
Anatis 15-punctata, 134 
Angoumois Grain Moth, 247 
Anisolabris maritima, 95 
Annulata, 1 
Anopheles crucians, 309 

quadrimaculatus, 307 
Anoplura, 164-167 

mouth parts of, 164 
Ant, Argentine, 371 

-lions, 224-225 

little brown, 204 

red, 373 
Ants, 186, 196, 197, 204, 367-374 

house, 373 

in lawns, 374 
Antennae, 8 
Anthomyiidse, 327-330 
Anthonomus grandis, 140 



Anthrax, 323 

Anthrenus scrophulariae, 104 

Antique tussock moth, 262 

Anuraphis roseus, 198 

Anus, 15 

Aorta, 19 

Apex, 14 

Aphidida;, 133, 187, 194-206, 291, 344, 

368, 370 
Aphis bakeri, 199 

-lions, 222 

maidi-radicis, 203 

pomi, 198 
Apis mellifera, 362 
Apoidea, 360-367 
Apple aphids, 198 

grain aphis, 198 

leafhoppers, 192 

maggot, 319 

-tree tent-caterpillar, 256 
Apterygota, 60, 62 

characters of, 62 
Arachnida, 2 

characters of, 4 
Arctiidse, 277-279 
Armored scales, 208, 209-216 
Army worm, 272 
Arsenate of lead, 46 

standard formula, 47 

of lime, 47 
Arsenic, 44 
Arthropod characters, 1 

groups of, 2 

distinctive table of, 5 
Arthropoda, 1 

Artificial control methods, 38 
Asilidffi, 316 
Asparagus beetle, 123 
Aspidiotus perniciosus, 211 
Attagenus piceus, 104 
Aulacaspis rosae, 214 
Australian roach, 78 
Automeris io, 286 
Axillary incision, 301 
Axillary sinus, 301 
375 



376 



INDEX 



B 



Bacillus pestis, 334 
Back-swimmers, 184 
Bacterial wilt, 118, 197 
Bag worms, 250-252 
Bark beetles, 146-149 
Basilarchia archippvis, 292 
Basilona imperialis, 281 
Bean weevils, 128-130 
Bedbug, 182 
Bee bread, 365 

moth, 249 
Bees, 360-367; 

bumble, 361 

carpenter, 361 

honey, 362 

leaf-cutter, 361 

solitary, 360 
Beetles, 98-149 
Beet-root louse, 205 
Belostomida;, 185 
BembecidsD, 354 
Bilateral symmetry, 2 
Bird lice, 161-163 
Birds, 1; and insects, 35, 36 
Biting lice, 161-163 
Black-beetle, 78 

carpet beetle, 104 

flies, 315 

lady beetle, 135 

scale, 135, 216, 220 

swallow-tail butterfly, 298 

witch, 269 
Blastophaga grossoruni, 349 
Blatella germanica, 70 
Blatta orientalis, 78 
Blattidaj, 76-78 
Blissus leucopterus, 174 
Blister beetles, 135-136 
Blood, 20 

vessels, 19 
Blue-bottle flies, 324 
Bombus, 361 
Bombycida), 255 
Bombyx mori, 255 
Book-lice, 159 
Borax, 50 

Bordeaux mixture, 54 
Bot flies, 318 
Brain, 21 

Breathing organs, 17 
Broad bean weevil, 129 



Bromius obscurus, 125 
Brown-tail moth, 265, 296, 297 
Bruchidie, 128-130 
Bruchophagus funebris, 349 
Bruchus chinensis, 129 

obtectus, 129 

pisorum, 128 

quadrimaculatus, 129 

rufimanus, 129 
Bubonic plague, 334 
Bud-worm (of corn), 120 
Buffalo carpet beetle, 104 

gnats, 315 

Tree-hopper, 190 
"Bug vs. bug," 220 
Buhach, 53 
Bumblebees, 361 
BuprestidiE, 105-107 
Burning insects, 40 
Butterflies, 290-299 

(and moths), 230-299 



Cabbage butterfly, imported, 293 

maggot, 327 
Caddice flies, 226-229 
Caeca, 16 
California devastating grasshopper, 83 

grape-root worm, 125 

oak worm, 267 
Caliroa cerasi, 341 
Callosamia promethea, 283 
Calosoma sycophanta, 100 
Camel crickets, 86 
Camnula pellucida, 84 
Camphor thrips, 158 
Canker worms, 253 
Cantharidin, 136 
Capsidaj, 180 
Carabida?, 100 
Carbon disulfid, 55 
Carnivorous diving beetles, 101 
Carolina grasshopper, 84 
Carpenter bees, 361 

moths, 234-236 

worm, 234 
Carrion beetles, 103 
Case-making clothes moth, 236 
Caterpillar, 232 
Catocalas, 269 
Cecropia moth, 283 
Cells, 13 



INDEX 



377 



Centipedes, 2 

characters of, 3 

Cephalothorax, 3, 151 

Cephus cinctus, 342 
pygmaeus, 342 

Cerambycidse, 130-133 

Ceratocampidte, 2S0 

Cercerida^, 354 

Ccrci, 14 

Cerosa bubal us, 190 

Chalcid fiies, 347-351 

Changa, 90 

Characters of Arthropods, 1 

Chermidffi, 187, 193 

Cherry plant lice, 205 

Chigoe, 336 

Chilocorus bivulnerus, 134, 213 

Chilopoda, 2 

characters of, 3 

China wax, 209 

Chinch bug, 174 

bug fungus, 176 

Chinese mantis, 79 

Chionaspis furfura, 210 

pinifoliaj, 215 
Chitin, 2, 7 

Chloridea obsoleta, 270 
Cholera, 321, 323 
Chordata, 1 
Chrysalis, 234 
Chrysidoidea, 353 
Chrysobothris femorata, 106 
Chrysomelida-, 11.5-128 
Chrysomphalus auraiitii, 215 
Chrysomyia mafellaria, 324 
Chrysopida-, 222-223 
Cicada-killer, 355 
Cicadas, 187-190, 355 
Cicadida;, 187-190 
Cicindelida', 101 
Cimex lectularius, 182 
Cirnicidai, 182 
Cyirculatory organs, 19 
Cirphis iinipuncta, 272 
Citheronia regalis, 280 
Citrus mealy bug, 218 
thrips, 157 
white fly, 207 
Classification, 59-61 
Clean culture, 39 
Clear-winged grasshopper, 84 

moths, 243-247 
Click-beetles, 107-110 



Closed cells, 13 
Clothes moths, 236-238 
Clover aphis, 199 

-flower midge, 311 
root-borer, 147 
-seed chalcid, 349 
Cnidocampa flavescens, 250, 353 
Coccida;, 187, 208-220 
Coccinella novemnotata, 134 
Coccinellida;, 133-135 
Coccotorus scutellaris, 139 
Cochineal, 209 
Cocoon, 29 

in Lepidoptera, 233 
Codling moth, 238 
Ca!lenterata, 1 
Coleomegilla fuscilabris, 134 
Coleoptera, 98-149 
Coleoptera vera, 99-136 
Collembola, 62, 63-64 
Colon, 16 

Colorado potato beetle, 115 
Comb, 364 

Combinations of sprays, 54 
Commissures, 21 
Common bean weevil, 129 
Compound eyes, 8 
Conotrachelus nenuphar, 137 
Contact insecticides, 43, 49-53 
Contarinia tritici, 314 
Control by natural methods, 35 
Coreida;, 172-173 
Corixidifi, 184 
Corn borer, European, 249 

ear worm, 270 
Cornicles, 195 
Corn-root aphis, 203, 370 

worms, 120-122 
Corrodentia, 159-161 
Corydalis cornuta, 221 
Cossidte, 234-236 
Costa, 14 

(Jotton boll weevil, 140 
stainer, 174 
worm, 269 
Cottony cushion scale, 135, 219, 
220 
maple scale, 217 
Cowpea weevil, 129 
Coxa, 12 
Crab louse, 166 
Crane flies, 304 
Crickets, 88-90 



378 



INDEX 



Crioceris asparagi, 123 

duodecimpunctata, 124 

Crop, 16 

rotation, 39 

Croton bug, 76 

Crude petroleum, 50 

Crustacea, 2 

characters of, 3 

Cryptolaemus montrouzieri, 135 

Cuckoo wasps, 353 

Cucurbit mosaic disease, 118 

Culex pipiens, 306 

Culicidaj, 305-311 

Curly-leaf disease, 193 

Currant worm, 340 

Cursorial Orthoptera, 75-81 

Cutworms, 275 

Cydnida?, 172 

Cylas formicarius, 145 

Cynipoidea, 346 



D 



Dagger moths, 270 

Damsel-flies, 68-69 

Danaidae, 291 

Danaus archippus, 291 

Darkling beetles, 135 

Dasyneura leguminicola, 311 

Datana, 267 

Death watch, 160 

Dengue, 310 

Dermaptera, 95-97 

Dermestes lardarius, 103 

Dermestida;, 103-105 

Diabrotica duodecimpunctata, 120 

longicornis, 121 

soror, 122 

trivittata, 119 

vergifera, 122 

vittata, 118 
Dialeurodes citri, 207 
Diapheromera femorata, 81 
Differential grasshopper, 83 
Digestion, 16 
Digestive organs, 15 
formation, 15 
Digger wasps, 354-356 
Dimorphism, seasonal, 291 
Dioptidae, 267 
Diplopoda, 2 

characters of, 3 
Diptera, 301-332 



Diseases carried by insects, 166, 167, 

183, 309, 321-323, 325, 334 
Diseases of insects, 178 
Dispersion of insects, 296 
Dissosteira Carolina, 84 
Dobson, 221 
Doodle-bug, 224 
Dog-day harvest-flies, 189 
Doryphora clivicollis, 117 
Dragon-flies, 68-71 
Drill-worm, 120 
Drones, 362, 363 
Dry sulfur compounds, 52 
Dusting poisons, 43 
Dynastes tityrus, 114 
Dysdercus suturellus, 174 
Dysentery, 321 
Dytiscidae, 101 
Dzierzon theory, 365, 369 



E 



Earwigs, 95-97 

Eccoptogaster rugulosus, 147 

Ecdysis, 27 

Echidnophaga gallinacea, 336 

Ecliinodermata, 1 

Eggs. 25 

Ejaculatory duct, 24 

Elaterida?, 107-110 

Electric-light bugs, 185 

Elm leaf beetle, 126 

Elytra, 98 

Embiidina, 74 

Emergence, 30 

Empoa rosse, 193 

Empoasca mali, 192 

Empodium, 12, 303 

Engraver beetles, 136, 146-149 

Ensign flies, 343 

Ephemerida, 65-67 

Ephestia kuhniella, 249 

Epipharynx, 9 

Erebus odorata, 269 

Eriosoma lanigera, 199 

Estigmene acra;a, 277 

Eucosmida;, 238-243 

Eulecanium nigrofasciatum, 217 

tulipiferaj, 216 
Eumenidae, 357 
Euproctis chrysorrhoea, 265 
European corn borer, 249 

earwig, 95 



INDEX 



379 



Eurymus eurytjieme, 295 

philodice, 295 
Evaniidip, 343 
Excretory organs, 21 
External skeleton, 2 
Eyed elater, 108 
Eyes, 8 

agglomerate, 9 



F 



Fall army worm, 274 
canker worm, 253 
webworm, 278 
False budworm of tobacco, 270 
Farm practices, 38 
Femur, 12 

Fever: Relapsing, 166 
Trench, 166 
Typhus, 166 
Fidia viticida, 125 
Field crickets, 88 
Fifteen-spotted Lady beetle, 134 
Fig fertilization by Blastophaga, 349 
Filariasis, 310 
Fire blight, 181, 197 

-flies, 100 
Fishes, 1 
Fish-flies, 222 
Flat-headed apple-tree borer, 106 

borers, 105-107 
Flax-seed stage, 312 
Flea-beetles, 122 
Fleas, 333-337 
Flesh flies, 326 
Flies, 301-332 
Fluted scale, 135, 219, 220 
Forceps in Thysanura, 63 

in Dermaptera, 95 
Fore-intestine, 15 
Forest tent-caterpillar, 259 
Forficula auricularia, 95 
Formicoidea, 367-374 
Four-spotted bean weevil, 129 
Frankliniella tritici, 154 
Frenal fold, 338 
hooks, 338 
Frenulum, 232 
Froghoppers, 191 
Fruit flies, 319-321 

tree bark-beetle, 147 
Fumigation, 18, 55 



G 

Gad flies, 314 
Galerucella luteola, 126 
Galleria melonella, 249 
Gall insects, 346 
midges, 311 
Galls: Aphid, 196, 202, 205 
Chalcidoid, 347 
Cynipoid, 346 
Itonidid, 311 
Trypetid, 319 
Gasoline torches, 40 
Gastric caeca, 16 
Gastrophilus, 319 
Gelechiidff, 247 
Geometridse, 252-255 
German honey bee, 362 

roach, 76 
Gerridae, 184 
Giant silkworms, 283-287 

water-bugs, 185 
Glossina, 325 
Glow-worms, 100 
Goat moth, 234 
Golden-eyes, 222 
Grape Phylloxera, 201 

-root worm, 125 
Grass-feeding Froghopper, 191 
Grasshoppers, 81-85 
thrips, 158 
worm, 274 
Green apple aphis, 198 
-bottle flies, 324 
fruit worms, 270 
grasshoppers, 85-87 
-heads, 315 
Japanese beetle, 114 
Greenhouse thrips, 155, 158 

white fly, 207 
Ground beetles, 100 
Groups of Arthropods, 2 

distinctive characters of, 5 
Grouse locusts, 85 
Gryllidff, 88-90 
Gryllus luctuosus, 88 
Guests in galls, 347 
Gypsy moth, 100, 262, 296 
Gyrinidae, 101 

H 

Halisidota caryae, 277 
Halteres, 14, 301 



380 



INDEX 



Hamuli, 338 
Hand picking, 40 
Harleqiiin bug, 171 
Harmolita grande, 348 

tritici, 348 
Harpalus caliginosus, 100, 117 
Harvest flies, Dog-day, 189 
Hawk moths, 287-290 
Head, 7 

Healthy crops, 39 
Hearing: in crickets, 88 

in grasshoppers, 85 

in green grasshoppers, 87 
Heart, 19 
Heat, 41 

Hedgehog caterpillar, 277 
Heliothrips hsemorrhoidalis, 155 
Hellebore, 48 
Hellgrammite, 221 
Hemerocampa leucostignia, 260 
Hemielytra, 168 
Hemimetabola, 26 
Hemiptera, 168-185 
Hemispherical scale, 218 
Hesperiidse, 290 
Hessian fly, 312 
Heterocera, 234 
Heterometabola, 26 
Hexapoda, 2 

characters of, 5 

as a class, 59 
"Hickory horned devil," 280 

tiger moth, 277 
Hind-intestine, 15 
Hippodamia convergens, 134 
Hive bee, 362 
Holometabola, 26 

development of, 27 
Homoptera, 186-220 
Honey, 364 

ants, 371 

bees, 362 

-dew, 186, 194, 195, 217, 368, 370 

sac, 364 
Hornets, 360 
Horn-tails, 343, 344 
Horse bot flies, 319 

flies, 314 
House ants, 373 

fly, 297, 321 

mosquito, 306 
Human body louse, 165 
Humming bird moths, 287-290 



Hydrocyanic acid gas, 57 
Hydrophilidffi, 102 
Hylemyia antiqua, 329 

brassicae, 327 
Hymenoptera, 338-374 
Hyperparasites, 344 
Hyphantria cunea, 278 
Hypoderma bovis, 318 

lineatum, 318 
Hypodermis, 7 
Hypognathous, 8 
Hypopharynx, 10 



Icerya purchasi, 135, 219 

Ichneumon flies, 343-346 

Ichneumonoidea, 343-346 

Ileum, 16 

Imaginal buds, 28 

Imago, 28 

Imperial moth, 281 

Imported cabbage butterfly, 293, 296 

Inch worms, 252-255 

Inquilines, 347, 361, 362 

Insecticides, 43 

classes of, 43 
Insect orders; their relations, 60 

powder, 53 
Insects, 2 

characters of, 5 

external structure of, 6 

internal structure of, 15 
Instar, 27 

Introduced insects, 35, 296 
lo moth, 286 
Ipidffi, 146-149 
Iridomyrmex humilis, 371 
Isabella tiger moth, 277 
Isia Isabella, 277 
Isoptera, 91-93 
Italian honey bee, 363 
Itonididie, 311-314 



Japanese beetle. Green, 114 
Japanese silkworm moth, 284 
Jelly-fish, 1 
Jerusalem crickets, 87 
Jigger flea, 336 
Jugum, 232 

Jumping plant lice, 187, 193 
June bugs, 110 



INDEX 



381 



K 

Kala-azar, 183 
Katydids, 85-87 
Kellogg, 349 
Kerosene emulsion, 49 



Labia minor, 95 

Labial palpus, 10 

Labium, 10 

Labrum, 9 

Lace bugs, 179 

Lace wings, 222 

Lady beetles, bugs or birds, 133-135 

Lamellicorn beetles, 110-115 

Lampyridae, 100 

Laphygma frugiperda, 274 

Larder beetle, 103 

Lasiocampidse, 256-260 

Lasius niger americanus, 204 

Laspeyresia pomonella, 238 

Leaf beetles, 115-128 

-cutter bees, 361 

hoppers, 187, 190, 191 

insects, 81 
Legs, 10, 12 

abdominal, 14 
Lenticels, 216 
Leopard Moth, 234 
Lepidoptera, 230-299 
Lepidosaphes beckii, 215 

ulmi, 209 
Lepisma saccharina, 03 
Leprosy, 183 

Leptinotarsa decimlineata, 115 
Lesser migratory grasshopper, 84 
Lice: biting, 161-163 

on animals, 166 

sucking, 164-167 
, Limacodida>, 250 
Lime-sulfur wash, 51 

self-boiled, 52 
Little brown ant, 204 

earwig, 95 
Lochhead, 269 
Longicorn beetles, 130-133 
Long-tailed mealy bug, 219 

Pelecinus, 351 

Thalessa, 345 
Losses by insects, 32 

crop, 32 

difficulties of estimation, 33 



Losses, health, 32 

figures on, 34 

increase in, 34 
"Lubber" grasshoppers, 84 
Luminous organs, 100, 109 
Luna moth, 280 
Lunula, 301 
Lycisnida', 290 
Lygajid*, 174 
Lygus pratensis, 181 
Lymantriida;, 260-266 

M 

Macrodactylus subspinosus, 113 
Macrolepidoptera, 234 
Maggots, 303 
Malacosoma americana, 256 

disstria, 259 
Malaria, 309 
Malarial mosquitoes, 307 
Mallophaga, 161-163 
Malpighian tubes, 21 
Mammals, 1 
Mandibles, 9 
Mantida), 78 
Mantis, common, 79 

Chinese, 79 

European, 79 

religiosa, 79 
Mantispa, 224 
Mantispidffi, 224 
Marlatt, 142 
Mask, 71 

Masked bedbug hunter, 182 
Mason wasps, 358 
Maxillae, 9 
Maxillary palpus, 10 
May beetles, 110 

-flies, 65-67 
Meadow plant-bug, 180 
Mealy bugs, 208, 218-220 

destroyer, 135 
Measuring worms, 252-255 
Mecoptera, 300 
Median segment, 12, 338 
Mediterranean flour moth, 249 
Melanoplus atlanis, 84 

bivittatus, 84 

devastator, 83 

differentialis, 83 

femur-rubrum, 83 

spretus, 82 
Melittia satyriniformis, 245 



382 



INDEX 



Meloidse, 13&-136 

Melophagus ovinus, 330 

Metamorphosis, 25 

Microlepidoptera, 234 

Mid-intestine, 15 

Millipedes, 2 

characters of, 3 

Miridaj, 180 

Miris dolobratus, 180 

Miscible oils, 50 

Miscellaneous control methods, 41 

Mites, 2 

Mole crickets, 88 

Mollusca, 1 

Molting, 26 

number of molts, 27 

Monarch, 291, 297 

Monomorium pharaonis, 373 

Mosquitoes, 305-311 

Moths, 234-290 

(and butterflies), 230-299 

Mouth cavity, 15 
parts, 9 

in Anoplura, 164 
in Apterygota, 62 
in Diptera, 302 
in Hemiptera, 168 
in Homoptera, 186 
in Hymenoptera, 339 
in Lepidoptera, 230 
in Siphonaptera, 333 
in Thysanoptera, 153 

Murgantia histrionica, 171 

Murky ground beetle, 100, 117 

Musca domestica, 321 

Muscidffi, 321-326 

Mutillidse, 356 

Myiasis, 318 

Myrmeleonidae, 224-225 



Nine-spotted lady beetle, 134 
Noctuidse, 268-277 
Nodus, 68 

Northern tobacco worm, 288 
Notodontidse, 266 
Notolophus antiqua, 262 
Notonectidae, 184 
Notum, 7 

Novius cardinalis, 135, 219 
Number of segments, 6 
Nymph, 27, 31 
Nymphalidffi, 292 

O 

Oak worm, California, 267 
Oat bhght, 197 
Ocelli, 8 
Odonata, 68-71 
ffisophagus, 16 
(Estridffi 318 
ffistrus ovis, 319 
Onion maggot, 329 

thrips, 155 
Orcus chalybeus, 135 
Orders: their relation, 60 
Oriental moth, 250, 353 

roach, 78 
Orneodidaj, 248 
Orthoptera, 7&-90 
Ovary, 23 

Overflow worm, 274 
Oviduct, 23 
Oviparous insects, 25 
Ovipositor, 14, 338 
Owlet moths, 268-277 
Ox warbles, 318 
Oyster-shell scale, 209, 220 



N 

Nagana, 326 

Natural control methods, 35 
Necrophorus, 103 
Negro-bugs, 172 
Nepida;, 185 
Nerve ganglia, 21 
Nervous system, 21 
Neuroptera, 221-225 
Neuters, 22 
Nicotine, 50, 56 
sulfate, 51 



Pacific peach borer, 243 

Paleacrita vernata 254 

Papilionidse, 298 

Papilio polyxenes, 298 

Paradichlorobenzine, 245 

Parasites 36, 344, 347 

Parasitism, 352 

Paratenodera sinensis, 79 

Paris green, 45 

Parthenogenesis: in aphids, 196 
in gall insects, 346 
in Thysanoptera, 154 



INDEX 



383 



;iae, 231 
Pea and bean weevils, 128-130 

louse, 205 

weevil, 128 
Peach Borer, 243 

"stop-back," 181 
Pear Psylla, 193 

slug, 341 

thrips, 156 
Pedicel, 338 

Pediculus humanus, 165 
Pelecinus polyturator, 351 
Pentatomidse, 171 
Pentilia misella, 134 
Periodical cicada, 187 
Periplaneta americana, 78 
Periplaneta australasiae, 78 
Petiole, 338, 354, 367 
Phasmidse, 80 
Philaenus lineatus, 191 
Philosamia cynthia, 284 
Phlegethontius quinquemaculata, 288 

sexta, 288 
Phryganidia californica, 267 
Phthirus pubis, 166 
Phyllophaga, 110 
Phylloxera vitifolise, 201 
Phymatidae, 182 
Phytonomus posticus, 143 
Phytophaga destructor, 312 
Picking by hand, 40 
Pieridaj, 293-296 
Pigeon Tremex, 343 
Pine-leaf scale, 215 

weevil, white, 142 
Pissodes strobi, 142 
Pitiful lady beetle, 134 
Plague, 183 
Plant lice, 133, 187, 194-206, 291, 344, 

368, 370 
Planting, time of, 40 
Plecoptera, 72-73 
Pleuron, 7 
Plowing, 39 
Plum curculio, 137 

gouger, 139 
Porthetria dispar, 262 
Poison baits, 47 
Polistes, 358 
Pollen baskets, 363 
Polyphemus moth, 283 
Pontia rapse, 293 
Popillia japonica, 114 



Potato plant louse, 205 

-stalk weevil, 145 
Praying mantids, 78 
Primary parasites, 344 
Prionoxystus robinise, 234 
Proctotrypoidea, 351 
Prognathous, 8 
Promethea moth, 283 
Prominents, 266 
Propodeum, 12, 338 
Propolis, 364 

Prospaltella perniciosi, 220 
Protective imitation, 292 
Protozoa, 1 
Proventriculus, 16 
Pseudococcus citri, 218 

longispinus, 219 
Pseudoscorpions, 2 
Psithyrus, 362 
Psocids, 159-161 
Psyllia pyricola, 193 
Psychidaj, 250-252 
Ptero mains puparum, 350 
Pteronidea ribesii, 340 
Pterophoridse, 248 
Pterygota, 60, 65 
Ptilinum, 301 
Pulchriphyllium scythe, 81 
Pulvillus, 12, 303 
Pulvinaria vitis, 217 
Pupa, 29 

libera, 99, 339 

obtecta, 30, 99 
Puparium, 29, 303 
Pupipara, 330-332 
Purple scale, 215 
Pyralida;, 248-250 
Pyrausta nubilalis, 249 
Pyrethrum, 53 
Pyrophorus spp. 109 
Pyrrhocoridse, 173 

R 

Railroad worm, 319 

Raphidiida?, 224 

Rear-horses, 78-80 

Rectal gills, 71 

Rectum, 16 

Red-humped apple-tree caterpillar, 267 

-legged grasshopper, 83 

scale, 215 
Reduviidse, 182 



384 



INDEX 



Relapsing fever, 166, 183 
Relations of insect orders, 60 
Repellents, 40 
Reproductive organs, 22 
Reptiles, 1 
Respiration, 17 
Reticulitermes flavipes, 93 
Rhagoletis pomonella, 319 
Rhinoceros beetles, 114 
Rhizobius ventralis, 135 
Rhopalocera, 234, 290-299 
Rhopalosiphum prunifolise, 198 
Rhynchophora, 99, 136-149 
Roaches, 76-78 
Robber flies, 316 
Rocky mountain locust, 82 
Rose chafer, 113 

leaf hopper, 193 

scale, 214 
Rostrum, 168 
Round-headed apple-tree borer, 131 

borers, 130-133 
Rove-beetles, 102 
Royal jelly, 366 

moths, 280 
Rusty tussock moth, 262 



S 



Saltatorial Orthoptora, 81-90 
Salt marsh caterpillar, 277 

mosquito, 307 
Samia cecropia, 283 
San Jose scale, 211, 220 
Saperda Candida, 131 
Sarcophagidae, 326 
Saturniidffi, 283-287 
Satyrida?, 293 
Saw-flies, 340-343 
Scale insects, 187, 208-220 
Scapteriscus vicinus, 90 
Scarabaeidai, 110-115 
Scarabsus, 110 
Schizura concinna, 267 
Scirtothrips citri, 157 
Sclerites, 7 
Scolytidse, 146-149 
Scorpion flies, 300 
Scorpions, 2 
Screw-worm fly, 324 
Scurfy scale, 210 
Scutellista cyanea, 220 
Scutellum, 168 



Sea urchin, 1 
Seasonal dimorphism, 291 
Secondary parasites, 344 
Seminal receptacle 23 
Sense organs, 22 
Serphoidea, 351 
Sesiida;, 243 

Seventeen-year locust, 187 
Sexes of insects, 22 
Shad-flies, 65 
Sheep bot fly, 319 

tick, 330 
Shell gland, 23 
Shellac, 209 
Shot-hole borer, 147 
Sialida;, 221 
Silk, 29, 255 

glands, 227, 233 
worm, 255 
Silpha americana, 103 
Silphidffi, 103 
Silver fish, 63 
Simulida?, 315 
Siphonaptera, 333-337 
Sitotroga cerealella, 247 
Skeleton, 7 
Skip-jacks, 107-110 
Skippers, 290 
Slave-making ants, 370 
Sleeping sickness, 325 
Slug caterpillars, 250 
Snails, 1 

Snapping-beetles, 107-110 
Snout beetles, 136-149 
Snow fleas, 64 
Soap, 50 

Social wasps, 356-360 
Sodium fluorid, 48 
Soft scales, 208, 216-218 
Solitary bees, 360 
Soothsayers, 78 
Sooty mould, 207 
Sounds produced by crickets, 88 

by grasshoppers, 85 

by green grasshoppers, 87 
Southern corn-root worm, 120 
Southern tobacco worm, 288 
Spanish flies, 136 
Span worms, 252-255 
Spermaries, 24 
Sphecius speciosus, 355 
Sphecoidea, 354-356 
Sphingids, 287-290 



INDEX 



385 



Spiders, 2 
Spinneret, 231, 233 
Spiracles, IS 
Spittle insects, 1!)1 
Sporotrichum globulifenun, 176 
Spotted lady beetle, 134 
Sprays, 44 

combinations of, 54 
Spring: canker worm, 254 
"Spring" of Collembola, 63 
Springtails, 63 
Squash bug, 172 
Squash-vine borer, 245 
Stagomantis Carolina, 79 
Stalk borers, 270 
Staphylinidse, 102 
Starfish, 1 

Steel-blue lad.y beetle, 135 
Stegomyia fasciata, 309 
Stem-mothers, 196 
Sternum, 7 
Sticktight flea, 336 
Sting, 14, 339 
Stinging ants, 356 
Stink bugs, 171 
Stomach, 16 

poisons, 43 

their action, 17 
Stone-flies, 72 

"Stop-back" of peaches, 181 
Strawberry thrips, 154 
Strepsiptera, 150-152 
Striped cucumber beetle, 118 
Stylops, 150-152 
Subojsophageal ganglion, 22 
Sucking Hce, 164—167 
Sulfur, 52, 56 

compounds, 52 
Sutures, 7 

Swallow-tail butterflies, 298 
Swarming; of ants, 369 

of honey bees, 365 

of white ants, 92 
Sweet potato weevil, 145 
Synanthedon exitiosa, 243 
Synanthedon opalescens, 243 
Syrphidse, 316 
Syrphus flies, 316 



TabanidiB, 314 

Table of classification, 61 

25 



Tachina flies, 273, 326 

Tachinida;, 326 

Taenidia, 334 

Ta^niothrips inconsequens, 156 

Tapestry moth, 237 

Tarantula-killer, 357 

Tarnished plant-bug, 181 

Tarsus, 12 

Tegula), 231, 338 

Telea polyphemus, 283 

Tenebrio molitor, 135 

Tenebrionida?, 135 

Tent-caterpillars, 256-260 

Tenthredinoidea, 340-343 

Terebrantia, 339 

Termites, 91-93 

Terrapin scale, 217 

Testes, 24 

Tettigoniidae, 85-87 

Thalessa, long-tailed, 345 

Thorax, 10 

Thread-waisted wasps, 354 

Three-spotted Doryphora, 117 

Thrips, 153-158 . 

Thrips tabaci, 155 

Thyridopteryx ephemerseformis, 252 

Thysanoptera, 153-158 

Thysanura, 62 

Tibia, 12 

Tibicen linnei, 189 

Tibicina septendecim, 187 

Ticks, 2 

Tiger beetles, 101 

moths, 277-279 
Time of planting, 40 
Tinea pellionella, 236 
Tineidse, 236-238 
Tineola biselliella, 236 
Tingididce, 179 
Tipulidie, 304 
Tobacco worms, 288 
Tomato fruitworm, 270 
Tortoise beetles, 128 
Trachea, 18 
Tracheal gills, 19, 71 
Trap crops, 40 

lanterns, 40 
Tree crickets, 90 

hoppers, 187, 190 
Tremex columba, 343 
Trench fever, 166 
Trichobaris trinotata, 145 
Trichophaga tapetzella, 237 



386 



INDEX 



Trichoptera, 22&-229 
Tropaea luna, 286 
True bugs, 170 
Trypanosoma gambiense, 325 
Trypetidse, 319-321 
Tsetse flies, 325 
Tussock moths, 260-266 
Twelve-spotted asparagus beetle, 124 

cucumber beetle, 120 
Twice-stabbed lady beetle, 134, 213 
Twisted-wing parasites, 150-152 
Two-spotted lady beetle, 133 

-striped grasshopper, 84 
Tuberculosis, 323 
Tulip tree scale, 216 
Tunga penetrans, 336 
Typhoid fever, 321, 323 
Typhus fever, 166 



U 



Underwings, 269 



Vagina, 23 

Value of honey and wax, 367 

Vas deferens, 24 

Vedalia, 135, 219, 220 

Velvet ants, 356 

Veratrum, 48 

Vespidse, 358 

Vespoidea, 356-360 

Vespula, 359 

Viceroy, 292 

Viviparous insects, 25, 196, 212 

W 

Walking-sticks, 80-81 

Wasps, progressive development in, 360 

Water-boatmen, 184 

"Water bugs," 76 

-scavenger beetles, 102 

-scorpions, 185 



Water skaters, 184 

Wax, 364 

Weather conditions and insects, 36 

Webbing clothes moth, 236 

Webster, 314 

Western corn-root worm, 121 

cricket, 87 

grass-stem borer, 342 

striped cucumber beetle, 119 

twelve-spotted cucumber beetle, 122 
Whale-oil soap, 50 
Wheat joint-worm, 348 

midge, 314 

-stem borer, 342 

straw-worm, 348 

thrips, 154 
Wheeler, 370 
Whirligig beetles, 101 
White ants, 91-93 

flies, 187, 206-208 

grubs, 110-113 

marked tussock moth, 260 

pine weevil, 142 
Wingless grasshoppers, 86 
Wings, 12-14 

veins, 13 
Wire worms, 108 
Woolly apple aphis, 199 

bears, 277 



X 



Xylocopa, 361 



Yaws, 323 

Yellow-jackets, 359 
fever, 309 
fever mosquito, 309 
meal-worm, 135 



Z 



Zoraptera, 94 






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